uniq - report or filter out repeated lines in a file
/usr/bin/uniq [-c | -d | -u] [-f fields] [-s char]
[input_file [output_file]]
/usr/bin/uniq [-c | -d | -u] [-n] [+ m] [input_file [output_file]]
uniq [-cdiu] [-D[delimit]] [-f fields] [-s chars] [-w chars]
[input_file [output_file]]
uniq [-cdiu] [-D[delimit]] [-n] [+m] [-w chars] [input_file [output_file]]
The uniq utility reads an input file comparing adjacent lines and writes
one copy of each input line on the output. The second and succeeding copies of
repeated adjacent input lines are not written.
Repeated lines in the input are not detected if they are not
adjacent.
The uniq built-in in ksh93 is associated with the /bin or
/usr/bin path. It is invoked when uniq is executed without a
pathname prefix and the pathname search finds a /bin/uniq or
/usr/bin/uniq executable.
uniq reads an input, comparing adjacent lines, and writing
one copy of each input line on the output. The second and succeeding copies
of the repeated adjacent lines are not written.
If output_file is not specified, uniq writes to
standard output. If input_file is not specified, or if
input_file is -, uniq reads from standard input, and
the start of the file is defined as the current offset.
The following options are supported by /usr/bin/uniq:
-c
Precedes each output line with a count of the number of
times the line occurred in the input.
-d
Suppresses the writing of lines that are not repeated in
the input.
-f fields
Ignores the first
fields fields on each input line
when doing comparisons, where
fields is a positive decimal integer. A
field is the maximal string matched by the basic regular expression:
[[:blank:]]*[^[:blank:]]*
If fields specifies more fields than appear on an input
line, a null string is used for comparison.
+m
Equivalent to -s chars with chars
set to m.
−n
Equivalent to -f fields with fields
set to n.
-s chars
Ignores the first chars characters when doing
comparisons, where chars is a positive decimal integer. If specified in
conjunction with the -f option, the first chars characters after
the first fields fields is ignored. If chars specifies more
characters than remain on an input line, a null string is used for
comparison.
-u
Suppresses the writing of lines that are repeated in the
input.
The following options are supported by the uniq built-in command is
ksh93:
-c
--count
Outputs the number of times each line occurred along with
the line.
-d
--repeated | duplicates
Outputs only duplicate lines.
-D
--all-repeated[=delimit]
Outputs all duplicate lines as a group with an empty line
delimiter specified by
delimit.
Specify delimit as one of the following:
none
Do not delimit duplicate groups.
prepend
Prepend an empty line before each group.
separate
Separate each group with an empty line.
The value for delimit can be omitted. The default value is
none.
-f
--skip-fields=fields
Skips over fields number of fields before checking
for uniqueness. A field is the minimal string matching the BRE
[[:blank:]]*[^[:blank:]]*.
-i
--ignore-case
Ignore case in comparisons.
+m
Equivalent to the -s chars option, with
chars set to m.
-n
Equivalent to the -f fields option, with
fields set to n.
-s
--skip-chars=chars
Skips over
chars number of characters before
checking for uniqueness.
If specified with the -f option, the first chars
after the first fields are ignored. If the chars specifies more
characters than are on the line, an empty string is used for comparison.
-u
--uniq
Outputs unique lines.
-w
--check-chars=chars
Skips over any specified fields and characters, then
compares chars number of characters.
The following operands are supported:
input_file
A path name of the input file. If input_file is
not specified, or if the input_file is −, the standard
input is used.
output_file
A path name of the output file. If output_file is
not specified, the standard output is used. The results are unspecified if the
file named by output_file is the file named by input_file.
Example 1 Using the uniq Command
The following example lists the contents of the uniq.test
file and outputs a copy of the repeated lines.
example% cat uniq.test
This is a test.
This is a test.
TEST.
Computer.
TEST.
TEST.
Software.
example% uniq -d uniq.test
This is a test.
TEST.
example%
The next example outputs just those lines that are not repeated in
the uniq.test file.
example% uniq -u uniq.test
TEST.
Computer.
Software.
example%
The last example outputs a report with each line preceded by a
count of the number of times each line occurred in the file:
example% uniq -c uniq.test
2 This is a test.
1 TEST.
1 Computer.
2 TEST.
1 Software.
example%
See environ(7) for descriptions of the following environment variables
that affect the execution of uniq: LANG, LC_ALL,
LC_CTYPE, LC_MESSAGES, and NLSPATH.
The following exit values are returned:
0
Successful completion.
>0
An error occurred.
See attributes(7) for descriptions of the following attributes:
| ATTRIBUTE
TYPE |
ATTRIBUTE VALUE |
| CSI |
Enabled |
| Interface Stability |
Committed |
| Standard |
See standards(7). |
| ATTRIBUTE
TYPE |
ATTRIBUTE VALUE |
| Interface Stability |
See below. |
The ksh93 built-in binding to /bin and
/usr/bin is Volatile. The built-in interfaces are Uncommitted.