gitcli - Git command-line interface and conventions
This manual describes the convention used throughout Git CLI.
Many commands take revisions (most often "commits", but
sometimes "tree-ish", depending on the context and command) and
paths as their arguments. Here are the rules:
•Options come first and then args. A subcommand
may take dashed options (which may take their own arguments, e.g.
"--max-parents 2") and arguments. You SHOULD give dashed options
first and then arguments. Some commands may accept dashed options after you
have already given non-option arguments (which may make the command
ambiguous), but you should not rely on it (because eventually we may find a
way to fix these ambiguities by enforcing the "options then args"
rule).
•Revisions come first and then paths. E.g. in
git diff v1.0 v2.0 arch/x86 include/asm-x86, v1.0 and
v2.0 are revisions and arch/x86 and include/asm-x86 are
paths.
•When an argument can be misunderstood as either a
revision or a path, they can be disambiguated by placing -- between
them. E.g. git diff -- HEAD is, "I have a file called HEAD in my
work tree. Please show changes between the version I staged in the index and
what I have in the work tree for that file", not "show the
difference between the HEAD commit and the work tree as a whole". You can
say git diff HEAD -- to ask for the latter.
•Without disambiguating --, Git makes a
reasonable guess, but errors out and asks you to disambiguate when ambiguous.
E.g. if you have a file called HEAD in your work tree, git diff HEAD is
ambiguous, and you have to say either git diff HEAD -- or git diff
-- HEAD to disambiguate.
•Because
-- disambiguates revisions and
paths in some commands, it cannot be used for those commands to separate
options and revisions. You can use
--end-of-options for this (it also
works for commands that do not distinguish between revisions in paths, in
which case it is simply an alias for
--).
When writing a script that is expected to handle random
user-input, it is a good practice to make it explicit which arguments are
which by placing disambiguating -- at appropriate places.
•Many commands allow wildcards in paths, but you
need to protect them from getting globbed by the shell. These two mean
different things:
$ git restore *.c
$ git restore \*.c
The former lets your shell expand the fileglob, and you are asking
the dot-C files in your working tree to be overwritten with the version in
the index. The latter passes the *.c to Git, and you are asking the
paths in the index that match the pattern to be checked out to your working
tree. After running git add hello.c; rm hello.c, you will not
see hello.c in your working tree with the former, but with the latter
you will.
•Just as the filesystem . (period) refers
to the current directory, using a . as a repository name in Git (a
dot-repository) is a relative path and means your current repository.
Here are the rules regarding the "flags" that you should
follow when you are scripting Git:
•Splitting short options to separate words (prefer
git foo -a -b to git foo -ab, the latter may not even
work).
•When a command-line option takes an argument, use
the stuck form. In other words, write git foo -oArg instead of
git foo -o Arg for short options, and git foo --long-opt=Arg
instead of git foo --long-opt Arg for long options. An option that
takes optional option-argument must be written in the stuck form.
•When you give a revision parameter to a command,
make sure the parameter is not ambiguous with a name of a file in the work
tree. E.g. do not write git log -1 HEAD but write git log -1 HEAD
--; the former will not work if you happen to have a file called
HEAD in the work tree.
•Many commands allow a long option --option
to be abbreviated only to their unique prefix (e.g. if there is no other
option whose name begins with opt, you may be able to spell
--opt to invoke the --option flag), but you should fully spell
them out when writing your scripts; later versions of Git may introduce a new
option whose name shares the same prefix, e.g. --optimize, to make a
short prefix that used to be unique no longer unique.
From the Git 1.5.4 series and further, many Git commands (not all
of them at the time of the writing though) come with an enhanced option
parser.
Here is a list of the facilities provided by this option
parser.
Commands which have the enhanced option parser activated all
understand a couple of magic command-line options:
-h
gives a pretty printed usage of the command.
$ git describe -h
usage: git describe [<options>] <commit-ish>*
or: git describe [<options>] --dirty
--contains find the tag that comes after the commit
--debug debug search strategy on stderr
--all use any ref
--tags use any tag, even unannotated
--long always use long format
--abbrev[=<n>] use <n> digits to display SHA-1s
Note that some subcommand (e.g. git grep) may behave
differently when there are things on the command line other than -h,
but git subcmd -h without anything else on the command line is meant
to consistently give the usage.
--help-all
Some Git commands take options that are only used for
plumbing or that are deprecated, and such options are hidden from the default
usage. This option gives the full list of options.
Options with long option names can be negated by prefixing
--no-. For example, git branch has the option --track
which is on by default. You can use --no-track to override
that behaviour. The same goes for --color and --no-color.
Commands that support the enhanced option parser allow you to
aggregate short options. This means that you can for example use git rm
-rf or git clean -fdx.
Commands that support the enhanced option parser accepts unique
prefix of a long option as if it is fully spelled out, but use this with a
caution. For example, git commit --amen behaves as if you typed
git commit --amend, but that is true only until a later version of
Git introduces another option that shares the same prefix, e.g. git
commit --amenity option.
You can write the mandatory option parameter to an option as a
separate word on the command line. That means that all the following uses
work:
$ git foo --long-opt=Arg
$ git foo --long-opt Arg
$ git foo -oArg
$ git foo -o Arg
However, this is NOT allowed for switches with an optional
value, where the stuck form must be used:
$ git describe --abbrev HEAD # correct
$ git describe --abbrev=10 HEAD # correct
$ git describe --abbrev 10 HEAD # NOT WHAT YOU MEANT
Many commands that can work on files in the working tree and/or in
the index can take --cached and/or --index options. Sometimes
people incorrectly think that, because the index was originally called
cache, these two are synonyms. They are not — these two
options mean very different things.
•The --cached option is used to ask a
command that usually works on files in the working tree to only work
with the index. For example, git grep, when used without a commit to
specify from which commit to look for strings in, usually works on files in
the working tree, but with the --cached option, it looks for strings in
the index.
•The --index option is used to ask a
command that usually works on files in the working tree to also affect
the index. For example, git stash apply usually merges changes recorded
in a stash entry to the working tree, but with the --index option, it
also merges changes to the index as well.
git apply command can be used with --cached and
--index (but not at the same time). Usually the command only affects
the files in the working tree, but with --index, it patches both the
files and their index entries, and with --cached, it modifies only
the index entries.
See also
https://lore.kernel.org/git/7v64clg5u9.fsf@assigned-by-dhcp.cox.net/
and
https://lore.kernel.org/git/7vy7ej9g38.fsf@gitster.siamese.dyndns.org/
for further information.
Some other commands that also work on files in the working tree
and/or in the index can take --staged and/or --worktree.
•--staged is exactly like --cached,
which is used to ask a command to only work on the index, not the working
tree.
•--worktree is the opposite, to ask a
command to work on the working tree only, not the index.
•The two options can be specified together to ask
a command to work on both the index and the working tree.