| KSH93(1) | User Commands | KSH93(1) |
ksh93, rksh93
— Korn Shell, a standard and restricted command and
programming language
ksh93 |
[+-abcefhikmnoprstuvxBCD]
[-R file]
[+-o
option] ... [-]
[arg ...] |
rksh93 |
[+-abcefhikmnoprstuvxBCD]
[-R file]
[+-o
option] ... [-]
[arg ...] |
ksh93 is a command and programming
language that executes commands read from a terminal or a file.
rksh93 is a restricted version of the command
interpreter ksh93. rksh93 is
used to set up login names and execution environments whose capabilities are
more controlled than those of the standard shell.
See Invocation for the meaning of arguments to the shell.
A metacharacter is defined as one of the following characters:
; & ( ) | < >
NEWLINE SPACE TABA blank is a TAB or a SPACE.
An identifier is a sequence of letters, digits, or underscores starting with a letter or underscore. Identifiers are used as components of variable names.
A vname is a sequence of one or more identifiers separated by a period (.) and optionally preceded by a period (.). vnames are used as function and variable names.
A word is a sequence of characters from the character set defined by the current locale, excluding non-quoted metacharacters.
A command is a sequence of characters in the syntax of the shell language. The shell reads each command and carries out the desired action either directly or by invoking separate utilities. A built-in command is a command that is carried out by the shell itself without creating a separate process. Some commands are built-in purely for convenience and are not documented in this manual page. Built-ins that cause side effects in the shell environment and built-ins that are found before performing a path search (see Execution) are documented in this manual page. For historical reasons, some of these built-ins behave differently than other built-ins and are called special built-ins.
A simple-command is a list of variable assignments (see Variable Assignments) or a sequence of blank-separated words which can be preceded by a list of variable assignments. See the Environment section of this manual page.
The first word specifies the name of the command to be
executed. Except as specified in this section, the remaining words are
passed as arguments to the invoked command. The command name is passed as
argument 0. See exec(2). The
value of a
simple-command is its exit status. If it terminates normally, its value is
between 0 and
255. If it
terminates abnormally, its value is
256 +
signum.
The name of the signal corresponding to the exit status can be obtained by
way of the -l option of the
kill built-in utility.
A pipeline is a sequence of one or more commands separated by |. The standard output of each command but the last is connected by a pipe(2) to the standard input of the next command. Each command, except possibly the last, is run as a separate process. The shell waits for the last command to terminate. The exit status of a pipeline is the exit status of the last command unless the pipefail option is enabled. Each pipeline can be preceded by the reserved word !. This causes the exit status of the pipeline to become 0 if the exit status of the last command is non-zero, and 1 if the exit status of the last command is 0.
A list is a sequence of one or more pipelines separated by ;, &, |&, &&, or |, and optionally terminated by ;, &, or |&. Of these five symbols, ;, &, and |& have equal precedence, which is lower than that of && and ||. The symbols && and || have equal precedence.
A semicolon (;) causes sequential execution of
the preceding pipeline. An ampersand (&) causes
asynchronous execution of the preceding pipeline, that is, the shell does
not wait for that pipeline to finish. The symbol
|& causes asynchronous execution of the preceding
pipeline with a two-way pipe established to the parent shell. The standard
input and output of the spawned pipeline can be written to and read from by
the parent shell by applying the redirection operators
<& and >& with
arg p to commands and by using
-p option of the built-in commands
read and print. The symbol
&& (||) causes the
list following it to be executed only if the preceding
pipeline returns a zero (non-zero) value. One or more NEWLINEs can appear in
a list instead of a semicolon, to delimit a command.
The first item of the first
pipeline of a list that is a
simple command not beginning with a redirection, and not occurring within a
while, until, or
if list, can be preceded by a
semicolon. This semicolon is ignored unless the showme
option is enabled as described with the set
built-in.
A command is either a simple-command or one of commands in the following list. Unless otherwise stated, the value returned by a command is that of the last simple-command executed in the command.
for
vname [in
word ...]
;do list
;doneEach time a for command is executed,
vname is set to the next
word taken from the in
word list. If in
word ... is omitted, the
for command executes the
do list once for each
positional parameter that is set starting from 1. Execution ends when
there are no more words in the list. See
Parameter Expansion.
for
(( [expr1] ;
[expr2] ;
[expr3] ))
;do list
;doneThe arithmetic expression expr1 is evaluated first. The arithmetic expression expr2 is repeatedly evaluated until it evaluates to zero and when non-zero, list is executed and the arithmetic expression expr3 is evaluated. If any expression is omitted, then it behaves as if it evaluated to 1. See Arithmetic Evaluation.
select
vname
[in
word ...]
;do list
;doneA select command prints on standard
error (file descriptor 2) the set of words, each
preceded by a number. If in word
... is omitted, the positional parameters starting from
1 are used instead. See
Parameter Expansion. The
PS3 prompt is printed and a line is read from
the standard input. If this line consists of the number of one of the
listed words, then the
value of the variable vname is set to the
word corresponding to this number. If this line is
empty, the selection list is printed again. Otherwise the value of the
variable vname is set to
NULL. The contents of the line read from
standard input is saved in the variable REPLY.
The list is executed for each selection until a
break or EOF is encountered. If the
REPLY variable is set to
NULL by the execution of
list, the selection list is printed before
displaying the PS3 prompt for the next
selection.
case
word in [
[(] pattern [|
pattern] ...
) list
;;]
... esacA case command executes the
list associated with the first
pattern that matches word.
The form of the patterns is the same as that used for file name
generation. See File Name
Generation.
The ;; operator causes execution
of case to terminate. If
;& is used
in place of ;; the next subsequent list, if any, is
executed.
if
list ;then
list [;elif
list ;then
list] ...
[;else list]
;fiThe list following
if is executed and, if it returns a
zero exit status, the list
following the first then is executed. Otherwise,
the list following elif is
executed, and, if its value is zero, the
list following the next
then is executed. Failing each successive
elif list, the
else list is executed. If
the if list has
non-zero exit status and there is no
else list, then the
if command returns a zero exit
status.
while
list ;do
list ;doneuntil
list ;do
list ;doneA while command repeatedly executes
the while list and, if the exit status of the last
command in the list is zero, executes the do
list, otherwise the loop terminates. If no
commands in the do list
are executed, then the while command returns a
zero exit status. until can be
used in place of while to negate the loop
termination test.
The expression is evaluated using the rules for arithmetic evaluation described in this manual page. If the value of the arithmetic expression is non-zero, the exit status is 0. Otherwise the exit status is 1.
Execute list in a separate environment. If two adjacent open parentheses are needed for nesting, a SPACE must be inserted to avoid evaluation as an arithmetic command as described in this section.
list is simply executed. Unlike the metacharacters, ( and ), { and } are reserved words and must occur at the beginning of a line or after a ; to be recognized.
Evaluates expression and returns a zero exit status when expression is true. See Conditional Expressions for a description of expression.
function
varname { list
;}Define a function which is referenced by varname. A function whose varname contains a dot (.) is called a discipline function and the portion of the varname preceding the last . must refer to an existing variable.
The body of the function is the list of
commands between { and }. A function
defined with the function
varname syntax can also be used as an argument to
the . special built-in command to get the equivalent
behavior as if the varname ()
syntax were used to define it. See
Functions.
namespace
identifier {
list
};Defines or uses the name space identifier and runs the commands in list in this name space. See Name Spaces.
time
[pipeline]If pipeline is omitted, the user and
system time for the current shell and completed child processes is
printed on standard error. Otherwise, pipeline is
executed and the elapsed time as well as the user and system time are
printed on standard error. The TIMEFORMAT
variable can be set to a format string that specifies how the timing
information should be displayed. See
Shell Variables for a
description of the TIMEFORMAT variable.
The following reserved words are recognized as reserved only when they are the first word of a command and are not quoted:
case |
do |
done |
else |
elif |
esac |
for |
fi |
function |
if |
select |
then |
time |
until |
while |
{ } |
| [[ ]] | ! |
One or more variable assignments can start a simple command or can
be arguments to the typeset,
enum, export,
or readonly special built-in
commands. The syntax for an assignment is of the
form:
No space is permitted between varname and the = or between = and word. The variable varname is unset before the assignment.
No space is permitted between varname and the =. An assignlist can be one of the following:
Indexed array assignment.
Associative array assignment. If prefixed by
typeset -a, creates
an indexed array instead.
Compound variable assignment. This creates a compound variable varname with sub-variables of the form varname.name, where name is the name portion of assignment. The value of varname contains all the assignment elements. Additional assignments made to sub-variables of varname are also displayed as part of the value of varname. If no assignments are specified, varname is a compound variable allowing subsequence child elements to be defined.
typeset
[options] assignment
...Nested variable assignment. Multiple assignments can be specified by separating each of them with a ;. The previous value is unset before the assignment.
.
filenameInclude the assignment commands contained in filename.
In addition, a += can be used in place of the = to signify adding to or appending to the previous value. When += is applied to an arithmetic type, word is evaluated as an arithmetic expression and added to the current value. When applied to a string variable, the value defined by word is appended to the value. For compound assignments, the previous value is not unset and the new values are appended to the current ones provided that the types are compatible. The right hand side of a variable assignment undergoes all the expansion listed below except word splitting, brace expansion, and file name generation. When the left hand side is an assignment is a compound variable and the right hand is the name of a compound variable, the compound variable on the right will be copied or appended to the compound variable on the left.
A word beginning with # causes that word
and all the following characters up to a NEWLINE to be commented, or
ignored.
The first word of each command is replaced by the text of an alias if an alias for this word has been defined. An alias name consists of any number of characters excluding metacharacters, quoting characters, file expansion characters, parameter expansion characters, command substitution characters, the characters / and =. The replacement string can contain any valid shell script including the metacharacters listed in the Commands section. The first word of each command in the replaced text, other than any that are in the process of being replaced, are tested for aliases. If the last character of the alias value is a BLANK then the word following the alias is also checked for alias substitution.
Aliases can be used to redefine built-in commands but cannot be
used to redefine the reserved words listed in the
Commands section. Aliases can be created
and listed with the alias command and can be removed
with the unalias command.
Aliasing is performed when scripts are read, not while they are
executed. For an alias to take effect, the alias
definition command has to be executed before the command which references
the alias is read. The following aliases are compiled into the shell but can
be unset or redefined:
autoload='typeset -fu'
command='command '
compound='typeset -C'
fc=hist
float='typeset -lE'
functions='typeset -f'
hash='alias -t --'
history='hist -l'
integer='typeset -li'
nameref='typeset -n'
nohup='nohup '
r='hist -s'
redirect='command exec'
source='command .'
stop='kill -s STOP'
suspend='kill -s STOP $$'
times='{ { time;} 2>&1;}'
type='whence -v'
After alias substitution is performed, each word is checked to see if it begins with an unquoted tilde (~). For tilde substitution, word also refers to the word portion of parameter expansion. See Parameter Expansion.
If it does, the word up to a / is checked to see
if it matches a user name in the password database. If a match is found, the
~ and the matched login name are replaced by the login
directory of the matched user. If no match is found, the original text is
left unchanged. A ~ by itself, or in front of a
/, is replaced by $HOME. A
~ followed by a + or -
is replaced by the value of $PWD and
$OLDPWD respectively.
In addition, when expanding a variable assignment, tilde substitution is attempted when the value of the assignment begins with a ~, and when a ~ appears after a colon (:). The : also terminates a ~ login name.
The standard output from a command enclosed in parentheses preceded by a dollar sign - $(list) - or in a brace group preceded by a dollar sign - ${ list;}, - or in a pair of grave accents - `` - can be used as part or all of a word. Trailing NEWLINEs are removed. In the second case, the { and } are treated as a reserved words so that { must be followed by a blank and } must appear at the beginning of the line or follow a ;. In the third (obsolete) form, the string between the quotes is processed for special quoting characters before the command is executed. See Quoting.
The command substitution $(cat file) can be replaced by the equivalent but faster $(<file). The command substitution $(n <#) expands to the current byte offset for file descriptor n. Except for the second form, the command list is run in a subshell so that no side effects are possible. For the second form, the final } will be recognized as a reserved word after any token.
An arithmetic expression enclosed in double parentheses preceded by a dollar sign - $((arithmetic_expression)) - is replaced by the value of the arithmetic expression within the double parentheses.
Each command argument of the form <(list) or >(list) runs process list asynchronously connected to some file in /dev/fd. The name of this file becomes the argument to the command. If the form with > is selected then writing on this file provides input for list. If < is used, then the file passed as an argument contains the output of the list process.
For example,
paste <(cut -f1 file1) <(cut -f3 file2) | tee \
>(process1) >(process2)
cuts fields 1 and 3 from the files file1 and file2 respectively, pastes the results together, and sends it to the processes process1 and process2. It also displays the results to the standard output. The file, which is passed as an argument to the command, is a UNIX pipe(2). Programs that expect to lseek(2) on the file do not work.
Process substitution of the form <(list) can also be used with the < redirection operator which causes the output of list to be standard input or the input for whatever file descriptor is specified.
A parameter is a variable, one or more digits, or any of the
characters *, @, #,
?, -, $, and
!. A variable is denoted by a vname.
To create a variable whose vname contains a
., a variable whose vname consists
of everything before the last . must already exist. A
variable has a value and zero or more attributes. Variables can be assigned
values and attributes by using the typeset special
built-in command. The attributes supported by the shell are described later
with the typeset special built-in command. Exported
variables pass values and attributes to the environment.
The shell supports both indexed and associative
arrays. An element of an array variable is referenced by a subscript. A
subscript for an indexed array is denoted by an arithmetic expression, (see
Arithmetic Evaluation),
between a [ and a ]. To assign values to
an indexed array, use
vname=(value
...) or set
-A vname value
.... The value of all subscripts must be in the
range of 0 to
4,194,303. A
negative subscript is treated as an offset from the maximum current index +1
so that -1 refers to the last element. Indexed arrays can be declared with
the -a option to typeset.
Indexed arrays need not be declared. Any reference to a variable with a
valid subscript is legal and an array will be created if necessary.
An associative array is created with the
-A option to typeset. A
subscript for an associative array is denoted by a string enclosed between
[ and ].
Referencing any array without a subscript is equivalent to referencing the array with subscript 0.
The value of a variable can be assigned by:
or
Note that no space is allowed before or after the =.
Attributes assigned by the
typeset special built-in command apply to all
elements of the array. An array element can be a simple variable, a compound
variable or an array variable. An element of an indexed array can be either
an indexed array or an associative array. An element of an associative array
can also be either. To refer to an array element that is part of an array
element, concatenate the subscript in brackets. For example, to refer to the
foobar element of an associative array that is defined
as the third element of the indexed array, use
${vname[3][foobar]}.
A nameref is a variable that is a reference
to another variable. A nameref is created with the
-n attribute of typeset. The
value of the variable at the time of the typeset
command becomes the variable that is referenced whenever the
nameref variable is used. The name of a
nameref cannot contain a dot (.). When a variable or
function name contains a dot (.) and the portion of the name up to the first
. matches the name of a nameref, the variable referred
to is obtained by replacing the nameref portion with
the name of the variable referenced by the nameref. If
a nameref is used as the index of a
for loop, a name reference is established for each
item in the list. A nameref provides a convenient way
to refer to the variable inside a function whose name is passed as an
argument to a function. For example, if the name of a variable is passed as
the first argument to a function, the command
typeset -n var=$1
inside the function causes references and assignments to
var to be references and assignments to the variable
whose name has been passed to the function. If any of the floating point
attributes, -E, -F or
-X, or the integer attribute,
-i, is set for vname, then the
value is subject to arithmetic evaluation as described
in this manual page. Positional parameters, parameters denoted by a number,
can be assigned values with the set special built-in
command. Parameter $0 is set from argument zero when the
shell is invoked.
The character $ is used to introduce substitutable parameters.
IFS.
In the above, word is not evaluated unless
it is to be used as the substituted string. In the following example,
pwd is executed only if d is not
set or is NULL:
print ${d:-$(pwd)}
If the colon (:) is omitted from the expression, the shell only checks whether parameter is set or not.
In the second form, the remainder of the value is used. A negative offset counts backwards from the end of parameter.
One or more BLANKs is required in front of a minus sign to prevent the shell from interpreting the operator as :-. If parameter is * or @, or is an array name indexed by * or @, then offset and length refer to the array index and number of elements respectively. A negative offset is taken relative to one greater than the highest subscript for indexed arrays. The order for associative arrays is unspecified.
When string is null, the pattern is deleted and the / in front of string can be omitted. When parameter is @, *, or an array variable with subscript @ or *, the substitution operation is applied to each element in turn. In this case, the string portion of word is re-evaluated for each element.
In the first form, only the first occurrence of pattern is replaced.
In the second form, each match for pattern is replaced by the specified string.
The third form restricts the pattern match to the beginning of the string.
The fourth form restricts the pattern match to the end of the string.
The following parameters are automatically set by the shell:
set command.This parameter is not set for commands which are asynchronous.
This parameter is also used to hold the name of the matching
MAIL file when checking for mail.
bg built-in command. Background jobs started in a
named pool with be in the form
pool.number where
pool is the pool name and
number is the job number within that pool.DEBUG trap, this variable
contains the current command line that is about to run.KEYBD trap. If the value
is changed as part of the trap action, then the new value replaces the key
(or key sequence) that caused the trap. See the
Key Bindings section of this manual
page.KEYBD trap.KEYBD
trap while in vi insert mode. Otherwise,
.sh.edmode is null when processing a
KEYBD trap. See the
vi Editing Mode section of this
manual page.KEYBD trap. The value is null when not processing
a KEYBD trap.cd
command.getopts built-in command.getopts built-in command.cd
command.RANDOM.select statement and
by the read built-in command when no arguments are
supplied.SHLVL is not in the environment
when the shell is invoked, it is set to 1.The following variables are used by the shell:
cd command.VISUAL variable is not set, the value of
this variable is checked for the patterns as described with
VISUAL and the corresponding editing option is
turned on.
See the set command in the
Special Commands section of
this manual page.
See the Invocation section of this manual page.
ENV is not set by the shell.
hist command. FCEDIT is
not used when HISTEDIT is set.
The shell specifies a default value to
FCEDIT.
-u attribute is referenced and
when a command is not found. If an executable file with the name of that
command is found, then it is read and executed in the current environment.
Unlike PATH, the current directory must be
represented explicitly by dot (.) rather than by
adjacent colon (:) characters or a beginning or ending
colon (:).hist
command.cd
command.
HOME is not set by the shell.
HOME is set by
login(1).
IFS variable is used to separate arguments for
the “$*” substitution. See the
Quoting section of this manual page.
Each single occurrence of an IFS
character in the string to be split, that is not in the
issspace character class, and any adjacent characters
in IFS that are in the
issspace character class, delimit a field. One or more
characters in IFS that belong to the
issspace character class, delimit a field. In
addition, if the same issspace character appears
consecutively inside IFS, this character is
treated as if it were not in the issspace class, so
that if IFS consists of two tab characters, then
two adjacent tab characters delimit a null field.
The shell specifies a default value to
IFS.
LC_ or LANG.LANG
variable and any other LC_ variable.LINES lines are filled.MAILPATH variable is not set, then the shell
informs the user of arrival of mail in the specified file.
MAIL is not set by the shell. On some
systems, MAIL is set by
login(1).
MAILPATH or MAIL
variables. The default value is
600
seconds. When the time has elapsed the shell checks before issuing the
next prompt.
The shell specifies a default value to
MAILCHECK.
MAILCHECK seconds. Each file name can be followed
by a ? and a message that is printed. The message
undergoes parameter expansion, command substitution, and arithmetic
substitution with the variable
$_
defined as the name of the file that has changed. The default message is
‘you have mail in $_’.PATH if executing under
rksh93. See the
Execution section of this
manual page.
The shell specifies a default value to
PATH.
The shell specifies a default value to
PS1.
The shell specifies a default value to
PS2.
The shell specifies a default value to
PS3.
PS4 is
+. When PS4 is unset, the
execution trace prompt is also +.
The shell specifies a default value to
PS4.
SHELL is not set by the shell. On some
systems, SHELL is set by
login(1).
time reserved word should be displayed. The
% character introduces a format sequence that is
expanded to a time value or other information.
The format sequences and their meanings are as follows.
l]Rl]Ul]SPThe braces denote optional portions. The optional p is a digit specifying the precision, the number of fractional digits after a decimal point. A value of 0 causes no decimal point or fraction to be output. At most three places after the decimal point can be displayed. Values of p greater than 3 are treated as 3. If p is not specified, the value 3 is used.
The optional l
specifies a longer format, including hours if greater than zero,
minutes, and seconds of the form
HHhMMmSS.FFs.
The value of p determines whether or not the
fraction is included.
All other characters are output without change and a trailing NEWLINE is added. If unset, the default value:
$'\nreal\t%2lR\nuser\t%2lU\nsys%2lS'is used. If the value is null, no timing information is displayed.
TMOUT is the
default time-out value for the read built-in
command. The select compound command terminates
after TMOUT seconds when input is from a terminal.
Otherwise, the shell terminates if a line is not entered within the
prescribed number of seconds while reading from a terminal. The shell can
be compiled with a maximum bound for this value which cannot be exceeded.
The shell specifies a default value to
TMOUT.
VISUAL overrides the value of
EDITOR.After parameter expansion and command substitution, the results of
substitutions are scanned for the field separator characters (those found in
IFS) and split into distinct fields where such
characters are found. Explicit null fields ( or
'') are retained. Implicit null fields, those resulting
from parameters that have no values or command substitutions with no output,
are removed.
If the braceexpand (-B)
option is set, each of the fields resulting from IFS
are checked to see if they contain one or more of the brace patterns. Valid
brace patterns are:
where * represents any character,
l1, l2 are letters and
n1, n2, n3
are signed numbers and fmt is a format specified as
used by printf. In each case, fields are created by
prepending the characters before the { and appending the
characters after the } to each of the strings generated by
the characters between the { and }. The
resulting fields are checked to see if they have any brace patterns.
In the first form, a field is created for each string between { and the first comma (‘,’), between a pair of commas (‘,’) and between the last comma (‘,’) and the terminating }. The string represented by * can contain embedded matching { and } without quoting. Otherwise, each { and } within * must be quoted.
In the second form, l1 and l2 must both be either upper case or both be lower case characters in the C locale. In this case a field is created for each character from l1 to l2 inclusive.
In the remaining forms, a field is created for each number starting at n1. This continues until it reaches n2 and increments n1 by n3. The cases where n3 is not specified behave as if n3 were 1 if n1 <= n2, and -1 otherwise.
In forms which specify %fmt, any format flags, widths and precisions can be specified and fmt can end in any of the specifiers cdiouxX. For example, {a,z}{1..5..3%02d}{b..c}x expands to the 8 fields, a01bx, a01cx, a04bx, a04cx, z01bx, z01cx, z04bx, and z04cx.
Following splitting, each field is scanned for the characters
*, ?, (, and
[, unless the -f option has been
set. If one of these characters appears, then the word is regarded as a
pattern.
Each file name component that contains any pattern
character is replaced with a lexicographically sorted set of names that
matches the pattern from that directory. If no file name is found that
matches the pattern, then that component of the file name is left unchanged
unless the pattern is prefixed with
~(N) in which case
it is removed. If FIGNORE is set, then each file
name component that matches the pattern defined by the value of
FIGNORE is ignored when generating the matching file
names. The names . and .. are also
ignored. If FIGNORE is not set, the character
. at the start of each file name component is ignored
unless the first character of the pattern corresponding to this component is
the character . itself. For other uses of pattern matching
the / and . are not specially
treated.
| alnum | alpha | blank | cntrl | digit | graph |
| lower | punct | space | upper | word | |
| xdigit |
word is equivalent to alnum plus the character _. Within [ and ], an equivalence class can be specified with the syntax [=c=] which matches all characters with the same primary collation weight (as defined by the current locale) as the character c. Within [ and ], [.symbol.] matches the collating symbol symbol.
A pattern-list is a list of one or more patterns separated from each other with an & or |. An & signifies that all patterns must be matched whereas | requires that only one pattern be matched. Composite patterns can be formed with one or more of the following sub-patterns:
By default, each pattern, or sub-pattern matches the longest string possible consistent with generating the longest overall match. If more than one match is possible, the one starting closest to the beginning of the string is chosen. However, for each of the compound patterns a - can be inserted in front of the ( to cause the shortest match to the specified pattern-list to be used.
When pattern-list is contained within parentheses, the backslash character (\) is treated specially even when inside a character class. All ANSI-C character escapes are recognized and match the specified character. In addition the following escape sequences are recognized:
A pattern of the form %(pattern-pairs) is a sub-pattern that can be used to match nested character expressions. Each pattern-pair is a two character sequence which cannot contain & or |. The first pattern-pair specifies the starting and ending characters for the match. Each subsequent pattern-pair represents the beginning and ending characters of a nested group that is skipped over when counting starting and ending character matches. The behavior is unspecified when the first character of a pattern-pair is alphanumeric except for the following:
%({}Q"E\), matches characters starting at { until the matching } is found not counting any { or } that is inside a double quoted string or preceded by the escape character (\). Without the {} this pattern matches any C language string.
Each sub-pattern in a composite pattern is numbered, starting at 1, by the location of the ( within the pattern. The sequence \n, where n is a single digit and \n, comes after the nth sub-pattern, matches the same string as the sub-pattern itself.
A pattern can contain sub-patterns of the form ~(options:pattern-list), where either options or :pattern-list can be omitted. Unlike the other compound patterns, these sub-patterns are not counted in the numbered sub-patterns. :pattern-list must be omitted for options F, G, N and V below. If options is present, it can consist of one or more of the following:
This is the default for K style patterns.
This is the default for K style patterns.
If both options and :pattern-list are specified, then the options apply only to pattern-list. Otherwise, these options remain in effect until they are disabled by a subsequent ~(...) or at the end of the sub-pattern containing ~(...).
Each of the metacharacters listed in the Definitions section of this manual page has a special meaning to the shell and causes termination of a word unless quoted. A character can be quoted, that is, made to stand for itself, by preceding it with a backslash (\). The pair \NEWLINE is removed. All characters enclosed between a pair of single quote marks ('') that is not preceded by a $ are quoted. A single quote cannot appear within the single quotes. A single quoted string preceded by an unquoted $ is processed as an ANSI-C string except for the following:
Inside double quote marks
(""),
parameter and command substitution occur and \ quotes the
characters \, `,
", and $. A $ in
front of a double quoted string is ignored in the C
or POSIX locale, and might cause the string to be
replaced by a locale specific string otherwise. The meaning of
$* and
$@ is
identical when not quoted or when used as a variable assignment value or as
a file name. However, when used as a command argument,
"$*"
is equivalent to
"$1d$2d...",
where d is the first character of the
IFS variable, whereas
"$@"
is equivalent to
"$1"
"$2" ... Inside grave quote marks
(``), \ quotes the characters
\, `, and $. If the
grave quotes occur within double quotes, then \ also
quotes the character ".
The special meaning of reserved words or aliases can be removed by quoting any character of the reserved word. The recognition of function names or built-in command names cannot be altered by quoting them.
The shell performs arithmetic evaluation for arithmetic
substitution, to evaluate an arithmetic command, to evaluate an indexed
array subscript, and to evaluate arguments to the built-in commands
shift and let. Arithmetic
evaluation is also performed on argument operands of the built-in command
printf that correspond to numeric format specifiers
in the format operand. See printf(1).
Evaluations are performed using double precision floating point arithmetic
or long double precision floating point for systems that provide this data
type. Floating point constants follow the ANSI-C
programming language floating point conventions. The floating point
constants Nan and Inf can be
used to represent "not a number" and infinity respectively.
Integer constants follow the ANSI-C programming language
integer constant conventions although only single byte character constants
are recognized and character casts are not recognized. Constants can be of
the form
[base#]n
where base is a decimal number between two and
sixty-four representing the arithmetic base and n is a
number in that base. The digits greater than
9 are
represented by the lower case letters, the upper case letters,
@, and _ respectively. For bases less
than or equal to
36, upper and
lower case characters can be used interchangeably.
An arithmetic expression uses the same syntax, precedence, and associativity of expression as the C language. All the C language operators that apply to floating point quantities can be used. In addition, the operator ** can be used for exponentiation. It has higher precedence than multiplication and is left associative. When the value of an arithmetic variable or subexpression can be represented as a long integer, all C language integer arithmetic operations can be performed. Variables can be referenced by name within an arithmetic expression without using the parameter expansion syntax. When a variable is referenced, its value is evaluated as an arithmetic expression.
Any of the following math library functions that are in the C math library can be used within an arithmetic expression:
In addition, arithmetic functions can be defined as shell
functions with a variant of the function
name syntax:
where name is the function name used in the arithmetic expression and each identified ident is a name reference to the long double precision floating point argument. The value of .sh.value when the function returns is the value of this function. User defined functions can take up to 3 arguments and override C math library functions.
An internal representation of a
variable as a double precision floating point can be
specified with the -E[n],
-F[n], or
-X[n] options of the
typeset special built-in command. The
-E option causes the expansion of the value to be
represented using scientific notation when it is expanded. The optional
option argument n defines the number of significant
figures. The -F option causes the expansion to be
represented as a floating decimal number when it is expanded. The optional
option argument n defines the number of places after
the decimal point in this case. The -X option causes
the expansion to be represented using the
%a format defined by
ISO C-99. The optional option argument n defines the number of places after
the decimal (or radix) point in this case.
An internal integer representation of a
variable can be specified with the
-i[n] option of the
typeset special built-in command. The optional
option argument n specifies an arithmetic base to be
used when expanding the variable. If you do not specify an arithmetic base,
base 10 is used.
Arithmetic evaluation is performed on the value of each assignment
to a variable with the -E,
-F, -X or
-i option. Assigning a floating point number to a
variable whose type is an integer causes the fractional part to be
truncated.
When used interactively, the shell prompts with the value of
PS1 after expanding it for parameter expansion,
command substitution, and arithmetic substitution, before reading a command.
In addition, each single ! in the prompt is replaced by
the command number. A !! is required to place a literal
! in the prompt. If at any time a NEWLINE is typed and
further input is needed to complete a command, then the secondary prompt,
that is, the value of PS2, is issued.
A conditional expression is used with the [[ compound command to test attributes of files and to compare strings. Field splitting and file name generation are not performed on the words between [[ and ]].
Each expression can be constructed from one or more of the following unary or binary expressions:
-a
fileThis option is the same as -e. This
option is obsolete.
-b
file-c
file-d
file-e
file-f
file-g
file-G
file-h
file-k
file-L
file-n
string-N
file-o
option-o
?option-O
file-p
file-r
file-R
name-s
file-S
file-t
fildes-u
file-v
name-w
file-x
file-z
string-ef
file2-nt
file2-ot
file2.sh.match array variable contains the match and
sub-pattern matches..sh.match array variable contains the match and
sub-pattern matches.In each of the above expressions, if file is of the form /dev/fd/n, where n is an integer, the test is applied to the open file whose descriptor number is n.
The following obsolete arithmetic comparisons are also supported:
-eq
exp2-ge
exp2-gt
exp2-le
exp2-lt
exp2-ne
exp2A compound expression can be constructed from these primitives by using any of the following, listed in decreasing order of precedence:
Before a command is executed, its input and output can be redirected using a special notation interpreted by the shell. The following can appear anywhere in a simple command or can precede or follow a command and are not passed on to the invoked command. Command substitution, parameter expansion, and arithmetic substitution occur before word or digit is used except as noted in this section. File name generation occurs only if the shell is interactive and the pattern matches a single file. Field splitting is not performed.
In each of the following redirections, if file is of the form /dev/sctp/ host/port, /dev/tcp/ host/port, or /dev/udp/ host/port, where host is a hostname or host address, and port is a service specified by name or an integer port number, then the redirection attempts to make a tcp, sctp or udp connection to the corresponding socket.
No intervening space is allowed between the characters of redirection operators.
-]wordCUR and EOF
evaluate to the current offset and end-of-file offset respectively when
evaluating expr.If one of the redirection operators is preceded by a digit, with no intervening space, then the file descriptor number referred to is that specified by the digit (instead of the default 0 or 1). If one of the redirection operators other than >&- and the ># and <# forms, is preceded by {varname} with no intervening space, then a file descriptor number > 10 is selected by the shell and stored in the variable varname. If >&- or the any of the ># and <# forms is preceded by {varname} the value of varname defines the file descriptor to close or position. For example:
... 2>&1means file descriptor 2 is to be opened for writing as a duplicate of file descriptor 1 and
exec [n]<filemeans open file for reading and store the file descriptor number in variable n. The order in which redirections are specified is significant. The shell evaluates each redirection in terms of the (file_descriptor, file) association at the time of evaluation. For example:
... 1>fname
2>&1first associates file descriptor 1 with file fname. It then associates file descriptor 2 with the file associated with file descriptor 1, that is, fname. If the order of redirections were reversed, file descriptor 2 would be associated with the terminal (assuming file descriptor 1 had been) and then file descriptor 1 would be associated with file fname. If a command is followed by & and job control is not active, the default standard input for the command is the empty file /dev/null. Otherwise, the environment for the execution of a command contains the file descriptors of the invoking shell as modified by input and output specifications.
The environment is a list of name-value pairs that is passed to an executed program in the same way as a normal argument list. See environ(7).
The names must be identifiers and the values
are character strings. The shell interacts with the environment in several
ways. On invocation, the shell scans the environment and creates a variable
for each name found, giving it the corresponding value and attributes and
marking it export. Executed commands inherit the
environment. If the user modifies the values of these variables or creates
new ones, using the export or
typeset -x commands, they
become part of the environment. The environment seen by any executed command
is thus composed of any name-value pairs originally inherited by the shell,
whose values can be modified by the current shell, plus any additions which
must be noted in export or
typeset -x commands. The
environment for any simple-command or function can be augmented by prefixing
it with one or more variable assignments. A variable assignment argument is
a word of the form
identifier=value.
Thus:
TERM=450 cmd argsand
(export TERM; TERM=450; cmd
args)are equivalent (as far as the execution of
cmd is concerned) except for
special built-in commands listed in the
Built-Ins section, those that are
preceded with a dagger. If the obsolete -k option is
set, all variable assignment arguments are placed in the environment, even
if they occur after the command name.
The following example first prints a=b c and then c:
echo a=b c set -k echo a=b c
This feature is intended for use with scripts written for early versions of the shell and its use in new scripts is strongly discouraged.
For historical reasons, there are two ways to define functions,
the name() syntax and the
function name syntax. These
are described in the Commands section of
this manual page.
Shell functions are read in and stored internally. Alias names are resolved when the function is read. Functions are executed like commands with the arguments passed as positional parameters. See the Execution section of this manual page for details.
Functions defined by the function
name syntax and called by name execute in the same
process as the caller and share all files and present working directory with
the caller. Traps caught by the caller are reset to their default action
inside the function. A trap condition that is not caught or ignored by the
function causes the function to terminate and the condition to be passed on
to the caller. A trap on EXIT set inside a function is
executed in the environment of the caller after the function completes.
Ordinarily, variables are shared between the calling program and the
function. However, the typeset special built-in
command used within a function defines local variables whose scope includes
the current function. They can be passed to functions that they call in the
variable assignment list that precedes the call or as arguments passed as
name references. Errors within functions return control to the caller.
Functions defined with the
name() syntax and functions defined
with the function name syntax
that are invoked with the . special built-in are
executed in the caller's environment and share all variables and traps with
the caller. Errors within these function executions cause the script that
contains them to abort.
The special built-in command return is
used to return from function calls.
Function names can be listed with the -f
or +f option of the typeset
special built-in command. The text of functions, when available, is also
listed with -f. Functions can be undefined with the
-f option of the unset
special built-in command.
Ordinarily, functions are unset when the shell executes a shell
script. Functions that need to be defined across separate invocations of the
shell should be placed in a directory and the FPATH
variable should contain the name of this directory. They can also be
specified in the ENV file.
Each variable can have zero or more discipline functions
associated with it. The shell initially understands the discipline names
get, set,
append, and unset but on
most systems others can be added at run time via the C programming interface
extension provided by the builtin built-in utility.
If the get discipline is defined for a variable, it
is invoked whenever the specified variable is referenced. If the variable
.sh.value is assigned a value inside the discipline
function, the referenced variable is evaluated to this value instead. If the
set discipline is defined for a variable, it is
invoked whenever the specified variable is assigned a value. If the
append discipline is defined for a variable, it is
invoked whenever a value is appended to the specified variable. The variable
.sh.value is specified the value of the variable before
invoking the discipline, and the variable is assigned the value of
.sh.value after the discipline completes. If
.sh.value is unset inside the
discipline, then that value is unchanged. If the
unset discipline is defined for a variable, it is
invoked whenever the specified variable is unset. The variable is not unset
unless it is unset explicitly from within this discipline function.
The variable .sh.name contains the name of the
variable for which the discipline function is called,
.sh.subscript is the subscript of the variable, and
.sh.value contains the value being assigned inside the
set discipline function. For the
set discipline, changing .sh.value
changes the value that gets assigned. The variable _ is a
reference to the variable including the subscript if any. For the
set discipline, changing .sh.value
will change the value that gets assigned. Finally, the expansion
${var.name}, when
name is the name of a discipline, and there is no variable of this name, is
equivalent to the command substitution
${var.name;}.
Commands and functions that are executed as part of the
list of a namespace command
that modify variables or create new ones, create a new variable whose name
is the name of the name space as given by identifier
preceded by two dots (..). When a variable whose name is
name is referenced, it is first searched for using
.identifier.name.
Similarly, a function defined by a command in the
namespace list is created
using the name space name preceded by two dots (..).
When the list of a
namespace command contains a
namespace command, the names of variables and
functions that are created consist of the variable or function name preceded
by the list of identifiers,
each preceded by two dots (..).
Outside of a name space, a variable or function created inside a name space can be referenced by preceding it with the name space name.
By default, variables staring with .sh are in the sh name space.
Typed variables provide a way to create data structure and
objects. A type can be defined either by a shared library, by the
enum built-in command described below, or by using
the -T option of the typeset
built-in command. With the -T option of
typeset, the type name, specified as an option
argument to -T, is set with a compound variable
assignment that defines the type. Function definitions can appear inside the
compound variable assignment and these become discipline functions for this
type and can be invoked or redefined by each instance of the type. The
function name
create
is treated specially. It is invoked for each instance of the type that is
created but is not inherited and cannot be redefined for each instance.
When a type is defined a special built-in command of that name is
added. These built-ins are declaration commands and follow the same
expansion rules as all the special built-in commands defined below that are
preceded by a dot (.). These commands can subsequently be
used inside further type definitions. The man page for these commands can be
generated by using the --man option or any of the
other -- options described with
getopts. The -r,
-a, -A,
-h and -S options of
typeset are permitted with each of these new
built-ins.
An instance of a type is created by invoking the type name
followed by one or more instance names. Each instance of the type is
initialized with a copy of the sub-variables except for sub-variables that
are defined with the -s option. Variables defined
with -S are shared by all instances of the type.
Each instance can change the value of any sub-variable and can also define
new discipline functions of the same names as those defined by the type
definition as well as any standard discipline names. No additional
sub-variables can be defined for any instance.
When defining a type, if the value of a sub-variable is not set
and the -r attribute is specified, it causes the
sub-variable to be a required sub-variable. Whenever an instance of a type
is created, all required sub-variables must be specified. These
sub-variables become readonly in each instance.
When unset is invoked on a sub-variable
within a type, and the -r attribute has not been
specified for this field, the value is reset to the default value
associative with the type. Invoking unset on a type
instance not contained within another type deletes all sub-variables and the
variable itself. A type definition can be derived from another type
definition by defining the first sub-variable name as _
and defining its type as the base type. Any remaining definitions will be
additions and modifications that apply to the new type. If the new type name
is the same is that of the base type, the type will be replaced and the
original type will no longer be accessible.
The typeset command with
-T and no option argument or operands will write all
the type definitions to standard output in a form that that can be read in
to create all the types.
If the monitor option of the set command
is turned on, an interactive shell associates a job with each pipeline. It
keeps a table of current jobs, printed by the jobs
command, and assigns them small integer numbers. When a job is started
asynchronously with &, the shell prints a line which
looks like:
[1] 1234indicating that the job which was started asynchronously was job number 1 and had one (top-level) process, whose process id was 1234.
If you are running a job and wish to stop it, CTRL-z
sends a STOP signal
to the current job. The shell normally displays a message that the job has
been stopped, and displays another prompt. You can then manipulate the state
of this job, putting it in the background with the
bg command, or run some other commands and then
eventually bring the job back into the foreground with the foreground
command fg. A CTRL-z takes effect immediately and is
like an interrupt in that pending output and unread input are discarded when
it is typed.
A job being run in the background stops if it tries to read from the terminal. Background jobs are normally allowed to produce output, but this can be disabled by giving the command stty tostop. If you set this tty option, then background jobs stop when they try to produce output like they do when they try to read input.
A job pool is a collection of jobs started with list & associated with a name.
There are several ways to refer to jobs in the shell. A job can be referred to by the process id of any process of the job or by one of the following:
In addition, unless noted otherwise, wherever a job can be specified, the name of a background job pool can be used to represent all the jobs in that pool.
The shell learns immediately whenever a process changes state. It
normally informs you whenever a job becomes blocked so that no further
progress is possible, but only just before it prints a prompt. This is done
so that it does not otherwise disturb your work. The notify option of the
set command causes the shell to print these job
change messages as soon as they occur.
When the monitor option is on, each background
job that completes triggers any trap set for
CHLD.
When you try to leave the shell while jobs are running or stopped, you are warned that
You can use the jobs command to see what
they are. If you immediately try to exit again, the shell does not warn you
a second time, and the stopped jobs are terminated. When a login shell
receives a HUP signal, it sends a HUP
signal to each job that has not been disowned with the
disown built-in command.
The
INT and
QUIT signals for an invoked command are ignored if the
command is followed by & and the
monitor option is not active. Otherwise, signals have the
values inherited by the shell from its parent. See the
trap built-in command.
Each time a command is read, the substitutions are carried out. If
the command name matches one of the ones in the
Special Built-in
Commands section of this manual page, it is executed within the current
shell process. Next, the command name is checked to see if it matches a user
defined function. If it does, the positional parameters are saved and then
reset to the arguments of the function call. A function is also executed in
the current shell process. When the function completes or issues a return,
the positional parameter list is restored. For functions defined with the
function name syntax, any trap
set on EXIT within the function is executed. The
exit value of a function is the value of the last command executed. If a
command name is not a special built-in command or a user defined function,
but it is one of the built-in commands, it is executed in the current shell
process.
The shell variables PATH and
FPATH define the search path for the directory
containing the command. Alternative directory names are separated by a colon
(:). The default path is
/bin:/usr/bin:,
specifying /bin, /usr/bin,
and the current directory in that order. The current directory can be
specified by two or more adjacent colons, or by a colon at the beginning or
end of the path list. If the command name contains a slash
(/), the search path is not used. Otherwise, each
directory in the list of directories defined by PATH
and FPATH is checked in order. If the directory
being searched is contained in the value of the
FPATH variable and contains a file whose name
matches the command being searched, then this file is loaded into the
current shell environment as if it were the argument to the
. command except that only preset aliases are
expanded, and a function of the specified name is executed as described in
this manual page.
If this directory is not in FPATH, the
shell first determines whether there is a built-in version of a command
corresponding to a given pathname and, if so, it is invoked in the current
process. If no built-in is found, the shell checks for a file named
.paths in this directory. If found and there is a
line of the form:
FPATH=pathwhere path is an existing directory, then
that directory is searched immediately after the current directory as if it
were found in the FPATH variable. If
path does not begin with /, it is
checked for relative to the directory being searched.
The .paths file is then checked for a line of the form:
PLUGIN_LIB=libname[:libname]...Each library named by libname will be
searched for as if it were an option argument to
builtin -f and, if it
contains a built-in of the specified name, this is executed instead of a
command by this name.
Any built-in loaded from a library found this way will be associated with the directory containing the .paths file so it will only execute if not found in an earlier directory.
Finally, the directory will be checked for a file of the given name. If the file has execute permission but is not an a.out file, it is assumed to be a file containing shell commands. A separate shell is spawned to read it. All non-exported variables are removed in this case. If the shell command file doesn't have read permission, and/or if the setuid and setgid bits are set on the file, then the shell executes an agent whose job it is to set up the permissions and execute the shell with the shell command file passed down as an open file. If the .paths contains a line of the form:
in the first or second line, then the environment variable
name is modified by prepending the directory specified
by value to the directory list. If
value is not an absolute directory, then it specifies
a directory relative to the directory in which the executable was found. If
the environment variable name does not already exist
it will be added to the environment list for the specified command. A
parenthesized command is executed in a sub-shell without removing
non-exported variables.
The text of the last HISTSIZE (default
512) commands entered from a terminal device is saved in a history file. The
file $HOME/.sh_history is used if the
HISTFILE variable is not set or if the file it names
is not writable. A shell can access the commands of all interactive shells
which use the same named HISTFILE. The built-in
command hist is used to list or edit a portion of
this file. The portion of the file to be edited or listed can be selected by
number or by giving the first character or characters of the command. A
single command or range of commands can be specified. If you do not specify
an editor program as an argument to hist then the
value of the variable HISTEDIT is used. If
HISTEDIT is unset, the obsolete variable
FCEDIT is used. If FCEDIT is
not defined, then /bin/ed is used. The edited
commands are printed and executed again upon leaving the editor unless you
quit without writing. The -s option (and in obsolete
versions, the editor name -) is used to skip the editing
phase and to re-execute the command. In this case a substitution parameter
of the form
old=new can be
used to modify the command before execution. For example, with the preset
alias r, which is aliased to hist
-s, typing ‘r bad=good c’ re-executes the most recent
command which starts with the letter c, replacing the
first occurrence of the string ‘bad’ with the string
‘good’.
Normally, each command line entered from a terminal device is
simply typed followed by a NEWLINE (RETURN or LINE FEED). If either the
emacs, gmacs, or vi
option is active, the user can edit the command line. To be in either of
these edit modes set the corresponding option. An editing option is
automatically selected each time the VISUAL or
EDITOR variable is assigned a value ending in either
of these option names.
The editing features require that the user's terminal accept RETURN as carriage return without line feed and that a SPACE must overwrite the current character on the screen.
Unless the multiline option is on, the
editing modes implement a concept where the user is looking through a window
at the current line. The window width is the value of
COLUMNS if it is defined, otherwise
80. If the window
width is too small to display the prompt and leave at least 8 columns to
enter input, the prompt is truncated from the left. If the line is longer
than the window width minus two, a mark is displayed at the end of the
window to notify the user. As the cursor moves and reaches the window
boundaries the window is centered about the cursor. The mark is a
> (<, *) if the
line extends on the right, left, or both sides of the window.
The search commands in each edit mode provide access to the history file. Only strings are matched, not patterns, although a leading ^ in the string restricts the match to begin at the first character in the line.
Each of the edit modes has an operation to list the files or
commands that match a partially entered word. When applied to the first word
on the line, or the first word after a ;,
|, &, or (, and
the word does not begin with ~ or contain a
/, the list of aliases, functions, and executable commands
defined by the PATH variable that could match the
partial word is displayed. Otherwise, the list of files that match the
specified word is displayed. If the partially entered word does not contain
any file expansion characters, a * is appended before
generating these lists. After displaying the generated list, the input line
is redrawn. These operations are called command name listing and file name
listing, respectively. There are additional operations, referred to as
command name completion and file name completion, which compute the list of
matching commands or files, but instead of printing the list, replace the
current word with a complete or partial match. For file name completion, if
the match is unique, a / is appended if the file is a
directory and a space is appended if the file is not a directory. Otherwise,
the longest common prefix for all the matching files replaces the word. For
command name completion, only the portion of the file names after the last
/ are used to find the longest command prefix. If only a
single name matches this prefix, then the word is replaced with the command
name followed by a space. When using a TAB for
completion that does not yield a unique match, a subsequent
TAB provides a numbered list of matching
alternatives. A specific selection can be made by entering the selection
number followed by a TAB.
The KEYBD trap can be used to intercept keys as they are typed and change the characters that are actually seen by the shell. This trap is executed after each character (or sequence of characters when the first character is ESC) is entered while reading from a terminal.
The variable .sh.edchar contains the character or character sequence which generated the trap. Changing the value of .sh.edchar in the trap action causes the shell to behave as if the new value were entered from the keyboard rather than the original value. The variable .sh.edcol is set to the input column number of the cursor at the time of the input. The variable .sh.edmode is set to ESC when in vi insert mode and is null otherwise. By prepending ${.sh.editmode} to a value assigned to .sh.edchar it causes the shell to change to control mode if it is not already in this mode.
This trap is not invoked for characters entered as arguments to editing directives, or while reading input for a character search.
This mode is entered by enabling either the emacs or gmacs option. The only difference between these two modes is the way they handle ^T. To edit, the user moves the cursor to the point needing correction and then inserts or deletes characters or words as needed. All the editing commands are control characters or escape sequences.
The notation for control characters is caret (^) followed by the character.
For example, ^F is the notation for CTRL/F. This is entered by depressing f while holding down the CTRL (control) key. The SHIFT key is not depressed. (The notation ^? indicates the DEL (delete) key).
The notation for escape sequences is
M- followed by a character. For example,
M-f (pronounced
Meta f) is entered
by depressing ESC (ASCII 033) followed by
‘f’.
M-F is the
notation for ESC followed by ‘F’.
All edit commands operate from any place on the line, not just at the beginning. The RETURN or the LINE FEED key is not entered after edit commands except when noted.
There are two typing modes. Initially, when you enter a command you are in the input mode. To edit, the user enters control mode by typing ESC (033) and moves the cursor to the point needing correction and then inserts or deletes characters or words as needed. Most control commands accept an optional repeat count prior to the command.
When in vi mode on most systems, canonical processing is initially enabled and the command is echoed again if the speed is 1200 baud or greater and it contains any control characters or less than one second has elapsed since the prompt was printed. The ESC character terminates canonical processing for the remainder of the command and the user can then modify the command line. This scheme has the advantages of canonical processing with the type-ahead echoing of raw mode.
If the option viraw is also set, the terminal is always have canonical processing disabled. This mode is implicit for systems that do not support two alternate end of line delimiters, and might be helpful for certain terminals.
By default the editor is in input mode.
The following input edit commands are supported:
The motion edit commands move the cursor.
The following motion edit commands are supported:
The search edit commands access your command history.
The following search edit commands are supported:
Same as / except that search is in the forward direction.
The following commands modify the line:
The following miscellaneous edit commands are supported:
hist
-e
${VISUAL:-${EDITOR:-vi}}
countin the input buffer. If count is omitted, the current line is used.
Otherwise, send the line after inserting a # in front of each line in the command.
This is command is useful for causing the current line to be inserted in the history as a comment and un-commenting previously commented commands in the history file.
Otherwise, replace the word at the current cursor location with the count item from the most recently generated command or file list. If the cursor is not on a word, it is inserted after the current cursor location.
The following simple-commands are executed in the shell process.
Input and output redirection is permitted. Unless otherwise indicated, the
output is written on file descriptor 1 and the exit
status, when there is no syntax error, is 0. Except for
:, true, false,
echo,
newgrp,
and
login,
all built-in commands accept -- to indicate the end
of options. They also interpret the option --man as
a request to display the manual page onto standard error and
-? as a help request which prints a usage message on
standard error.
In the list below, commands that are preceded by one or two + symbols are special built-in commands and are treated specially in the following ways:
: [arg
...]. name
[arg ...]function name reserved word
syntax, the function is executed in the current environment (as if it had
been defined with the name()
syntax). Otherwise if name
refers to a file, the file is read in its entirety and the commands are
executed in the current shell environment. The search path specified by
PATH is used to find the directory containing the
file. If any arguments arg are specified, they
become the positional parameters while processing the
. command and the original positional parameters
are restored upon completion. Otherwise the positional parameters are
unchanged. The exit status is the exit status of the last command
executed.
alias [-ptx]
[name[=value]]
...alias
with no arguments prints the list of aliases in the form
name=value
on standard output. The -p option causes the word
alias to be inserted before each one. When one or more arguments are
specified, an alias is defined for each name whose
value is specified. A trailing space in
value causes the next word to be checked for alias
substitution. The obsolete -t option is used to
set and list tracked aliases. The value of a tracked alias is the full
pathname corresponding to the specified name. The
value becomes undefined when the value of PATH is
reset but the alias remains tracked. Without the
-t option, for each name in
the argument list for which no value is specified,
the name and value of the alias is printed. The obsolete
-x option has no effect. The exit status is
non-zero if a name is specified,
but no value, and no alias has been defined for the
name.
bg
[job ...]break [n]for,
while, until, or
select loop, if any. If n is
specified, then break n levels.
builtin
[-ds] [-f
file] [name
...]-f option is specified, the built-ins are printed
on standard output. The -s option prints only the
special built-ins. Otherwise, each name represents
the pathname whose basename is the name of the built-in. The entry point
function name is determined by prepending b_ to the
built-in name. A built-in specified by a pathname will only be executed
when that pathname would be found during the path search. Built-ins found
in libraries loaded via the .paths file will be
associated with the pathname of the directory containing the
.paths file.
The ISO C/C++ prototype is
int
b_mycommand(int
argc, char **argv, Shbltin_t
*context); for the built-in command
mycommand where argv is an
array of argc elements and
context is an optional pointer to a
Shbltin_t structure as described in
<ast/shell.h> Special
built-ins cannot be bound to a pathname or deleted. The
-d option deletes each of the specified
built-ins. On systems that support dynamic loading, the
-f option names a shared library containing the
code for built-ins. The shared library prefix and/or suffix, which
depend on the system, can be omitted. Once a library is loaded, its
symbols become available for subsequent invocations of
builtin. Multiple libraries can be specified
with separate invocations of the builtin
command. Libraries are searched in the reverse order in which they are
specified. When a library is loaded, it looks for a function in the
library whose name is
lib_init()
and invokes this function with an argument of 0.
cd
[-LP] [arg]cd
[-LP] old
newIn the first form it changes the current directory to
arg. If arg is a literal
-, the directory is changed to the previous directory.
The shell variable HOME is the default
arg. The variable PWD is
set to the current directory. The shell variable
CDPATH defines the search path for the directory
containing arg. Alternative directory names are
separated by a colon (:). The default path is
NULL (specifying the current directory). The
current directory is specified by a null path name, which can appear
immediately after the equal sign or between the colon delimiters
anywhere else in the path list. If arg begins with
a /, the search path is not used. Otherwise, each
directory in the path is searched for arg.
The second form of cd substitutes the
string new for the string
old in the current directory name,
PWD, and tries to change to this new
directory.
By default, symbolic link names are treated literally when
finding the directory name. This is equivalent to the
-L option. The -P option
causes symbolic links to be resolved when determining the directory. The
last instance of -L or
-P on the command line determines which method
is used. The cd command cannot be executed by
rksh93.
command
[-pvVx] name
[arg ...]-v or -V
options, executes name with the arguments specified
by arg.
The -p option
causes a default path to be searched rather than the one defined by the
value of PATH. Functions are not searched when
finding name. In addition, if
name refers to a special built-in, none of the
special properties associated with the leading daggers are honored. For
example, the predefined alias
redirect='command
exec' prevents a script from terminating when an invalid
redirection is specified.
With the -x option, if command
execution would result in a failure because there are too many
arguments, E2BIG, the shell invokes command
name multiple times with a subset of the arguments
on each invocation. Arguments that occur prior to the first word that
expands to multiple arguments and after the last word that expands to
multiple arguments are passed on each invocation. The exit status is the
maximum invocation exit status.
With the -v option,
command is equivalent to the built-in
whence command described in this section. The
-V option causes command
to act like whence -v.
continue [n]for,
while, until, or
select loop. If n is
specified, then resume at the
nth enclosing loop.
disown
[job ...]echo
[arg ...]echo is system dependent and
print or printf described
in this section should be used. See
echo(1) for usage and description.
enum [-i]
type[=(value
...)]-i is specified
the values are case insensitive.
eval [arg ...]exec [-c]
[-a name
...] [arg
...]-c option causes the environment to
be cleared before applying variable assignments associated with the exec
invocation. The -a option causes
name rather than the first
arg, to become argv[0] for the
new process. Input and output arguments can appear and affect the current
process. If arg is not specified, the effect of this
command is to modify file descriptors as prescribed by the input/output
redirection list. In this case, any file descriptor numbers greater than
2 that are
opened with this mechanism are closed when invoking another program.
exit [n]set.
export [-p]
[name[=value]]
...export command is the same as
typeset -x except that if you use
export within a function, no local variable is
created. The -p option causes the word export to
be inserted before each one. Otherwise, the specified
name s are marked for automatic export to the
environment of subsequently-executed commands.
falseuntil for infinite loops.
fg
[job ...]getconf
[name [pathname]]The pathname argument is required for
parameters whose value depends on the location in the file system. If no
arguments are specified, getconf prints the
names and values of the current configuration parameters. The pathname
/ is used for each of the parameters that
requires pathname.
getopts
[-a name]
optstring vname
[arg ...]-- ends the options. Options beginning with
+ are only recognized when
optstring begins with a +.
optstring contains the letters that
getopts recognizes. If a letter is followed by a
:, that option is expected to have an argument. The
options can be separated from the argument by blanks. The option
-? causes getopts to
generate a usage message on standard error. The -a
option can be used to specify the name to use for the usage message, which
defaults to $0. getopts places
the next option letter it finds inside variable
vname each time it is invoked. The option letter is
prepended with a + when arg begins
with a +. The index of the next
arg is stored in OPTIND. The
option argument, if any, gets stored in OPTARG. A
leading : in optstring causes
getopts to store the letter of an invalid option
in OPTARG, and to set vname
to ? for an unknown option and to :
when a required option argument is missing. Otherwise,
getopts prints an error message. The exit status
is non-zero when there are no more options. There is no
way to specify any of the options :,
+, -, ?,
[, and ]. The option
# can only be specified as the first option.
hist
[-e ename]
[-nlr] [first
[last]]hist
-s
[old=new]
[command]HISTSIZE commands that were typed at the terminal.
The arguments first and last
can be specified as a number or as a string. A string is used to locate
the most recent command starting with the specified string. A negative
number is used as an offset to the current command number. If the
-l option is selected, the commands are listed on
standard output. Otherwise, the editor program ename
is invoked on a file containing these keyboard commands. If
ename is not supplied, then the value of the
variable HISTEDIT is used. If
HISTEDIT is not set, then
FCEDIT (default /bin/ed)
is used as the editor. When editing is complete, the edited command(s) is
executed if the changes have been saved. If last is
not specified, then it is set to first. If
first is not specified, the default is the previous
command for editing and -16 for listing. The
option -r reverses the order of the commands and
the option -n suppresses command numbers when
listing. In the second form, command is interpreted
as first described in this section and defaults to
the last command executed. The resulting command is executed after the
optional substitution
old=new is
performed.
jobs
-lnp [job
...]-l
option lists process ids in addition to the normal information. The
-n option only displays jobs that have stopped or
exited since last notified. The -p option causes
only the process group to be listed. See
Jobs for a description of the format of
job.
kill
[-s signame]
job ...kill
[-n signum]
job ...kill
-Ll [sig
...]-n option or by name
with the -s option (as specified in
<signal.h>, stripped of
the prefix ‘SIG’ with the exception
that
SIGCLD
is named CHLD). For backwards compatibility, the
n and s can be omitted and the number
or name placed immediately after the -. If the
signal being sent is TERM (terminate) or
HUP (hang up), then the job or process is sent a
CONT
(continue) signal if it is stopped. The argument job
can be the process id of a process that is not a member of one of the
active jobs. See Jobs for a description of
the format of job. In the third form,
kill -l or
kill -L, if
sig is not specified, the signal names are listed.
The -l option lists only the signal names whereas
-L lists each signal name and corresponding
number. Otherwise, for each sig that is a name, the
corresponding signal number is listed. For each sig
that is a number, the signal name corresponding to the least significant 8
bits of sig is listed.
let
[arg ...]let only recognizes octal constants
starting with 0 when the set
option letoctal is on. See the
Arithmetic Evaluation
section of this manual page for a description of arithmetic expression
evaluation. The exit status is 0 if the value of the
last expression is non-zero, and 1
otherwise.
newgrp [arg ...]exec
/bin/newgrp arg
...
print
[-CRenprsv] [-u
unit] [-f
format] [arg
...]--, each arg is printed on
standard output. The -f option causes the
arguments to be printed as described by printf. In
this case, any -e, -n,
-r, or -R options are
ignored. Otherwise, unless the -R or
-r options are specified, the following escape
conventions are applied:
The -R option prints all subsequent
arguments and options other than -n. The
-e causes the escape conventions to be applied.
This is the default behavior. It reverses the effect of an earlier
-r. The -p option causes
the arguments to be written onto the pipe of the process spawned with
|& instead of standard output. The
-v option treats each arg
as a variable name and writes the value in the
printf %B format. The
-C option treats each arg
as a variable name and writes the values in the
printf %#B format. The
-s option causes the arguments to be written
onto the history file instead of standard output. The
-u option can be used to specify a one digit
file descriptor unit number unit on which the
output is placed. The default is 1. If the option
-n is used, no NEWLINE is added to the
output.
printf
format [arg
...]print.pwd
[-LP]-L option is the default. It prints the logical
name of the current directory. If the -P option is
specified, all symbolic links are resolved from the name. The last
instance of -L or -P on
the command line determines which method is used.
read [-ACSprsv]
[-d delim]
[-n n | -N n]
[-t timeout]
[-u unit]
[vname?prompt]
[name ...]The shell input mechanism. One line is read and is broken up
into fields using the characters in IFS as
separators. The escape character, \, is used to remove
any special meaning for the next character and for line continuation.
The -d option causes the read to continue to the
first character of delim rather than NEWLINE. The
-n option causes at most n
bytes to read rather a full line but returns when reading from a slow
device as soon as any characters have been read. The
-N option causes exactly n
to be read unless an end-of-file has been encountered or the read times
out because of the -t option. In raw mode,
-r, the \ character is not
treated specially. The first field is assigned to the first
vname, the second field to the second
vname, etc., with leftover fields assigned to the
last vname. When vname has
the binary attribute and -n or
-N is specified, the bytes that are read are
stored directly into the variable. If -v is
specified, then the value of the first vname is
used as a default value when reading from a terminal device. The
-A option causes the variable
vname to be unset and each field that is read to
be stored in successive elements of the indexed array
vname. The -C option
causes the variable vname to be read as a compound variable. Blanks will
be ignored when finding the beginning open parenthesis. The
-S option causes the line to be treated like a
record in a .csv format file so that double quotes can be used to allow
the delimiter character and the new-line character to appear within a
field. The -p option causes the input line to be
taken from the input pipe of a process spawned by the shell using
|&. If the -s option is
present, the input is saved as a command in the history file. The option
-u can be used to specify a one digit file
descriptor unit unit to read from. The file
descriptor can be opened with the exec special
built-in command. The default value of unit n is
0. The option -t is used to
specify a time out in seconds when reading from a terminal or pipe. If
vname is omitted, then
REPLY is used as the default
vname. An end-of-file with the
-p option causes cleanup for this process so
that another can be spawned. If the first argument contains a
?, the remainder of this word is used as a prompt on
standard error when the shell is interactive. The exit status is
0 unless an end-of-file is encountered or read has
timed out.
readonly [-p]
[vname[=value]]
...-p option causes the word
readonly to be inserted before each one.
Otherwise, the specified
vnames are marked
readonly and these names cannot be changed by
subsequent assignment.
return [n]set
[+-BCGabefhkmnoprstuvx]
[+-o
[option]] ...
[+-A vname]
[arg ...]set command supports the following options:
-a-A-b-B-C-eif, while or
until command or in the pipeline following
!, if a command has a non-zero exit status, execute
the ERR trap, if set, and exit. This mode is
disabled while reading profiles.-f-G-h-k-m-n-oThe following argument can be one of the following option names:
allexport-a.bgnicebraceexpand-B.emacserrexit-e.globstar-G.gmacsignoreeofexit must be used.keyword-k.letoctallet command allows octal constants
starting with 0.markdirsmonitor-m.multilinenoclobber-C.noexec-n.noglob-f.nolognotify-b.nounset-u.pipefailprivileged-p.showmextrace option were enabled but is not
executed. Otherwise, the leading ; is
ignored.trackall-h.verbose-v.vivirawxtrace-x.If no option name is supplied, the current options settings are printed.
-pENV file. This mode is on whenever the
effective uid (gid) is not equal
to the real uid (gid). Turning
this off causes the effective uid and
gid to be set to the real uid and
gid.-r-s-t-u-v-x--As an obsolete feature, if the first
arg is - then the
-x and -v options are
turned off and the next arg is treated as the
first argument. Using + rather than
- causes these options to be turned off. These
options can also be used upon invocation of the shell. The current set
of options can be found in
$-. Unless
-A is specified, the remaining arguments are
positional parameters and are assigned, in order, to $1 $2
.... If no arguments are specified, then the names and values of all
variables are printed on the standard output.
shift [n]sleep
secondstrap [-p]
[action] [sig] ...-p option causes the trap action associated
with each trap as specified by the arguments to be printed with
appropriate quoting. Otherwise, action is processed
as if it were an argument to eval when the shell
receives signal(s) sig. Each
sig can be specified as a number or as the name of
the signal. Trap commands are executed in order of signal number. Any
attempt to set a trap on a signal that was ignored on entry to the current
shell is ineffective. If action is omitted and the
first sig is a number, or if
action is -, then the trap(s) for
each sig are reset to their original values. If
action is the null string then this signal is
ignored by the shell and by the commands it invokes. If
sig is ERR then
action is executed whenever a command has a
non-zero exit status. If sig is
DEBUG
then action is executed before each command. The
variable .sh.command contains the contents of the
current command line when action is running. If
sig is 0 or EXIT
and the trap statement is executed inside the body of a function defined
with the function name
syntax, then the command action is executed after
the function completes. If sig is
0 or EXIT for a trap set outside any
function then the command action is executed on exit
from the shell. If sig is KEYBD,
then action is executed whenever a key is read while
in emacs, gmacs, or
vi mode. The
trap
command with no arguments prints a list of commands associated with each
signal number.
truetypeset
[+-ACHSfblmnprtux]
[+-EFLRXZi[n]]
[+-M [mapname]]
[-T [tname=(assign_list)]]
[-h str]
[-a [type]]
[vname[=value]]Sets attributes and values for shell variables and functions. When invoked inside a function defined with the function name syntax, a new instance of the variable vname is created, and the variable's value and type are restored when the function completes.
Using + rather than
- causes these options to be turned off. If no
vname arguments are specified, a list of
vnames (and optionally the
values) of the variables
is printed. Using + rather than
-- keeps the values from being printed. The
-p option causes typeset
followed by the option letters to be printed before each name rather
than the names of the options. If any option other than
-p is specified, only those variables which have
all of the specified options are printed. Otherwise, the
vnames and
attributes of all
variables that have attributes are printed.
The following list of attributes can be specified:
-a-A-b-Z is also specified, the size in bytes of the
data in the buffer is determined by the size associated with the
-Z. If the base64 string
assigned results in more data, it is truncated. Otherwise, it is
filled with bytes whose value is zero. The
printf format %B can
be used to output the actual data in this buffer instead of the
base64 encoding of the data.-C-E-f-t, -u, and
-x. The -t option
turns on execution tracing for this function. The
-u option causes this function to be marked
undefined. The FPATH variable is searched to
find the function definition when the function is referenced. If no
options other than -f are specified, then the
function definition is displayed on standard output. If
+f is specified, then a line containing the function
name followed by a shell comment containing the line number and path
name of the file where this function was defined, if any, is
displayed. The names refer to function names rather than variable
names. No assignments can be made and the only other valid options are
-S, -t,
-u and -x. The
-S option can be used with discipline
functions defined in a type to indicate that the function is static.
For a static function, the same method will be used by all instances
of that type no matter which instance references it. In addition, it
can only use value of variables from the original type definition.
These discipline functions cannot be redefined in any type instance.
The -t option turns on execution tracing for
this function. The -u option causes this
function to be marked undefined. The FPATH
variable will be searched to find the function definition when the
function is referenced. If no options other than
-f are specified, then the function definition
will be displayed on standard output. If +f is
specified, then a line containing the function name followed by a
shell comment containing the line number and path name of the file
where this function was defined, if any, is displayed. The exit status
can be used to determine whether the function is defined so that
typeset -f
.sh.math.name will return
0 when math function name is
defined and non-zero otherwise.
The -i attribute cannot be
specified with -f.
-F-h-f the information is associated with the
corresponding discipline function.-H-iThe -i attribute cannot be
specified along with -R,
-L, -Z, or
-f.
-l-i, -E or
-F to indicate long integer, or long float.
Otherwise, all upper-case characters are converted to lower-case. The
upper-case option, -u, is turned off.
Equivalent to -M
tolower.-L-R option is turned off.
The -i attribute cannot be
specified with -L.
-m-M-n-p-R-L
option is turned off.
The -i attribute cannot be
specified with -R.
-r-Sfunction reserved word, the specified
variables will have function static scope.
Otherwise, the variable is unset prior to processing the assignment
list.-t-T-u-i specifies unsigned
integer. Otherwise, all lower-case characters are converted to
upper-case. The lower-case option, -l, is
turned off. Equivalent to -M
toupper.-x-X%a format
of ISO-C99. If n is non-zero, it defines the
number of hex digits after the radix point that is used when expanding
vname. The default is 10.-Z-L option has not
been set. Remove leading zeros if the -L
option is also set. If n is
non-zero, it defines the width of the field,
otherwise it is determined by the width of the value of first
assignment.
The -i attribute cannot be
specified with -Z.
ulimit
[-HSacdfmnpstv] [limit]If no option is specified, -f is
assumed.
The following are the available resource limits:
-a-c-d-f-HA hard limit cannot be increased once it is set.
If neither the -H nor
-S option is specified, the limit applies to
both. The current resource limit is printed when
limit is omitted. In this case, the soft limit
is printed unless -H is specified.
-m-n-p-s-SA soft limit can be increased up to the value of the hard limit.
If neither the -H nor
-S option is specified, the limit applies to
both. The current resource limit is printed when
limit is omitted. In this case, the soft limit
is printed unless -H is specified.
-t-vumask
[-S] [mask]If a symbolic value is specified, the new
umask value is the complement of the result of
applying mask to the complement of the previous
umask value. If mask is omitted,
the current value of the mask is printed. The -S
option causes the mode to be printed as a symbolic value. Otherwise, the
mask is printed in octal.
See umask(2)
unalias [-a]
name ...-a option causes all the aliases
to be unset.
unset [-fnv]
vname ...-f option is set, then the names
refer to function names. If the -v option is set,
then the names refer to variable names. The -f
option overrides -v. If -n
is set and name is a name reference, then
name is unset rather than the variable that it
references. The default is equivalent to -v.
Unsetting LINENO,
MAILCHECK, OPTARG,
OPTIND, RANDOM,
SECONDS, TMOUT, and
_ removes their special meaning even if they are
subsequently assigned to.
wait
[job]whence
[-afpv] name
...-v option produces
a more verbose report. The -f option skips the
search for functions. The -p option does a path
search for name even if name is an alias, a
function, or a reserved word. The -a option is
similar to the -v option but causes all
interpretations of the specified name to be reported.If the shell is invoked by
exec(2), and the first character of
argument zero ($0) is -, then the shell
is assumed to be a login shell and commands are read from
/etc/profile and then from either
.profile in the current directory or
$HOME/.profile, if either file exists. Next, for
interactive shells, commands are read first from
/etc/ksh.kshrc, and then from the file named by
performing parameter expansion, command substitution, and arithmetic
substitution on the value of the environment variable
ENV, if the file exists. If the
-s option is not present and
arg is specified and a file by the name of
arg exists, then it reads and executes this script.
Otherwise, if the first arg does not contain a
/, a path search is performed on the first
arg to determine the name of the script to execute.
The script arg must have execute permission and any
setuid and setgid settings are ignored.
If the script is not found on the path, arg is
processed as if it named a built-in command or function.
Commands are then read as described, and the following options are interpreted by the shell when it is invoked:
-c-c option is present, then commands are
read from the first arg. Any remaining arguments
become positional parameters starting at 0.-D-EENV variable or by
$HOME/.kshrc if not defined after the
profiles.-i-i option is present or if the shell input
and output are attached to a terminal (as told by
tcgetattr(3C))), this shell is
interactive. In this case TERM is ignored (so that
kill 0 does not kill an
interactive shell) and
INTR is
caught and ignored (so that wait is interruptible). In all cases,
QUIT is ignored by the shell.-R
filename-R filename option is
used to generate a cross reference database that can be used by a separate
utility to find definitions and references for variables and
commands.-r-r option is present, the shell is a
restricted shell.-s-s option is present or if no arguments
remain, then commands are read from the standard input. Shell output,
except for the output of the
Special Commands listed, is
written to file descriptor 2.The remaining options and arguments are described under the
set command. An optional -
as the first argument is ignored.
rksh93 is used to set up login names and execution environments whose capabilities are more controlled than those of the standard shell.
The actions of rksh93 are identical to
those of ksh93, except that the following are
disallowed:
SHELL, ENV,
FPATH, or PATHcommand -p to invoke
a command.These restrictions are enforced after
.profile and the ENV files
are interpreted.
When a command to be executed is found to be a shell procedure,
rksh93 invokes ksh93 to
execute it. Thus, it is possible to provide to the end-user shell procedures
that have access to the full power of the standard shell, while imposing a
limited menu of commands. This scheme assumes that the end-user does not
have write and execute permissions in the same directory. The net effect of
these rules is that the writer of the .profile has
complete control over user actions, by performing guaranteed setup actions
and leaving the user in an appropriate directory (probably not the login
directory). The system administrator often sets up a directory of commands,
for example, /usr/rbin, that can be safely invoked
by rksh93.
See largefile(7) for the
description of the behavior of ksh93 and
rksh93 when encountering files greater than or equal
to 2 Gbyte ( 2^31 bytes).
ENV is not set.The following exit values are returned:
If the shell is being used non-interactively, then execution of the shell file is abandoned unless the error occurs inside a sub-shell in which case the sub-shell is abandoned.
Run time errors detected by the shell are reported by printing the command or function name and the error condition. If the line number that the error occurred on is greater than one, then the line number is also printed in square brackets ([]) after the command or function name.
See the ksh93
exit command for additional details.
The scripting interface is Uncommitted. The environment variables, .paths feature, and editing modes are Volatile.
cat(1), cd(1), chmod(1), cut(1), date(1), echo(1), egrep(1), env(1), fgrep(1), grep(1), login(1), newgrp(1), paste(1), perl(1), printf(1), stty(1), test(1), umask(1), vi(1), dup(2), exec(2), fork(2), ioctl(2), lseek(2), pathconf(2), pipe(2), ulimit(2), umask(2), rand(3C), sysconf(3C), tcgetattr(3C), wait(3C), a.out(5), profile(5), attributes(7), environ(7), largefile(7), standards(7)
Bolsky, Morris I. and Korn, David G., The New KornShell Command and Programming Language, Prentice Hall, 1995..
POSIX-Part 2: Shell and Utilities, IEEE Std 1003.2-1992, ISO/IEC 9945-2, IEEE, 1993..
ksh93 scripts should choose shell function
names outside the namespace used by reserved keywords of the ISO C99, C++
and JAVA languages to avoid collisions with future enhancements to
ksh93.
If a command is executed, and then a command with the same name is
installed in a directory in the search path before the directory where the
original command was found, the shell continues to
exec the original command. Use the
-t option of the alias command to correct this
situation.
Some very old shell scripts contain a caret (^) as a synonym for the pipe character (|).
Using the hist built-in command within a
compound command causes the whole command to disappear from the history
file.
The built-in command .
file reads the whole file before any commands are
executed. alias and unalias
commands in the file do not apply to any commands defined in the file.
Traps are not processed while a job is waiting for a foreground process. Thus, a trap on CHLD is not executed until the foreground job terminates.
It is a good idea to leave a space after the comma operator in arithmetic expressions to prevent the comma from being interpreted as the decimal point character in certain locales.
There might be some restrictions on creating a .paths file which is portable across other operating systems.
If the system supports the 64-bit instruction set,
/bin/ksh93 executes the 64-bit version of
ksh93.
| March 8, 2021 | OmniOS |