Ubuntu Manpage: gitcli - Git command line interface and conventions

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NAME

       gitcli - Git command line interface and conventions

SYNOPSIS

       gitcli

DESCRIPTION

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:

• 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 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 asking 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.

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 checkout -- *.c
$ git checkout -- \*.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:

• it’s preferred to use the non dashed form of Git commands, which means that you should prefer git foo
to git-foo.

• 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.

ENHANCED OPTION PARSER

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.

Magic Options
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

--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.

Negating 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.

Aggregating short options
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.

Abbreviating long options
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.

Separating argument from the 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

NOTES ON FREQUENTLY CONFUSED OPTIONS

       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 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 http://marc.info/?l=git&m=116563135620359 and http://marc.info/?l=git&m=119150393620273 for
       further information.

GIT

       Part of the git(1) suite

Git 1.9.1                                          11/27/2018                                          GITCLI(7)