git/Documentation/git-sh-setup.txt

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git-sh-setup(1)
===============
NAME
----
git-sh-setup - Common Git shell script setup code
SYNOPSIS
--------
[verse]
'. "$(git --exec-path)/git-sh-setup"'
DESCRIPTION
-----------
This is not a command the end user would want to run. Ever.
This documentation is meant for people who are studying the
Porcelain-ish scripts and/or are writing new ones.
The 'git sh-setup' scriptlet is designed to be sourced (using
`.`) by other shell scripts to set up some variables pointing at
the normal Git directories and a few helper shell functions.
Before sourcing it, your script should set up a few variables;
`USAGE` (and `LONG_USAGE`, if any) is used to define message
given by `usage()` shell function. `SUBDIRECTORY_OK` can be set
if the script can run from a subdirectory of the working tree
(some commands do not).
The scriptlet sets `GIT_DIR` and `GIT_OBJECT_DIRECTORY` shell
variables, but does *not* export them to the environment.
FUNCTIONS
---------
die::
exit after emitting the supplied error message to the
standard error stream.
usage::
die with the usage message.
set_reflog_action::
set the message that will be recorded to describe the
end-user action in the reflog, when the script updates a
ref.
git_editor::
runs an editor of user's choice (GIT_EDITOR, core.editor, VISUAL or
EDITOR) on a given file, but error out if no editor is specified
and the terminal is dumb.
is_bare_repository::
outputs `true` or `false` to the standard output stream
to indicate if the repository is a bare repository
(i.e. without an associated working tree).
cd_to_toplevel::
runs chdir to the toplevel of the working tree.
require_work_tree::
require-work-tree wants more than what its name says Somebody tried "git pull" from a random place completely outside the work tree, while exporting GIT_DIR and GIT_WORK_TREE that are set to correct places, e.g. GIT_WORK_TREE=$HOME/git.git GIT_DIR=$GIT_WORK_TREE/.git export GIT_WORK_TREE GIT_DIR cd /tmp git pull At the beginning of git-pull, we check "require-work-tree" and then "cd-to-toplevel". I _think_ the original intention when I wrote the command was "we MUST have a work tree, our $(cwd) might not be at the top-level directory of it", and no stronger than that. That check is a very sensible thing to do before doing cd-to-toplevel. We check that the place we would want to go exists, and then go there. But the implementation of require_work_tree we have today is quite different. I don't have energy to dig the history, but currently it says: test "$(git rev-parse --is-inside-work-tree 2>/dev/null)" = true || die "fatal: $0 cannot be used without a working tree." Which is completely bogus. Even though we may happen to be just outside of it right now, we may have a working tree that we can cd_to_toplevel back to. Add a function "require_work_tree_exists" that implements the check this function originally intended (this is so that third-party scripts that rely on the current behaviour do not have to get broken). For now, update _no_ in-tree scripts, not even "git pull", as nobody on the list seems to really care about the above corner case workflow that triggered this. Scripts can be updated after vetting that they do want the "we want to make sure the place we are going to go actually exists" semantics. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-05-05 02:11:18 +00:00
checks if the current directory is within the working tree
of the repository, and otherwise dies.
require_work_tree_exists::
checks if the working tree associated with the repository
exists, and otherwise dies. Often done before calling
cd_to_toplevel, which is impossible to do if there is no
working tree.
require_clean_work_tree <action> [<hint>]::
checks that the working tree and index associated with the
repository have no uncommitted changes to tracked files.
Otherwise it emits an error message of the form `Cannot
<action>: <reason>. <hint>`, and dies. Example:
+
----------------
require_clean_work_tree rebase "Please commit or stash them."
----------------
get_author_ident_from_commit::
outputs code for use with eval to set the GIT_AUTHOR_NAME,
GIT_AUTHOR_EMAIL and GIT_AUTHOR_DATE variables for a given commit.
mergetools/p4merge: create a base if none available Originally, with no base, Git gave P4Merge $LOCAL as a dummy base: p4merge "$LOCAL" "$LOCAL" "$REMOTE" "$MERGED" Commit 0a0ec7bd changed this to: p4merge "empty file" "$LOCAL" "$REMOTE" "$MERGED" to avoid the problem of being unable to save in some circumstances with similar inputs. Unfortunately this approach produces much worse results on differing inputs. P4Merge really regards the blank file as the base, and once you have just a couple of differences between the two branches you end up with one a massive full-file conflict. The 3-way diff is not readable, and you have to invoke "difftool MERGE_HEAD HEAD" manually to get a useful view. The original approach appears to have invoked special 2-way merge behaviour in P4Merge that occurs only if the base filename is "" or equal to the left input. You get a good visual comparison, and it does not auto-resolve differences. (Normally if one branch matched the base, it would autoresolve to the other branch). But there appears to be no way of getting this 2-way behaviour and being able to reliably save. Having base==left appears to be triggering other assumptions. There are tricks the user can use to force the save icon on, but it's not intuitive. So we now follow a suggestion given in the original patch's discussion: generate a virtual base, consisting of the lines common to the two branches. This is the same as the technique used in resolve and octopus merges, so we relocate that code to a shared function. Note that if there are no differences at the same location, this technique can lead to automatic resolution without conflict, combining everything from the 2 files. As with the other merges using this technique, we assume the user will inspect the result before saving. Signed-off-by: Kevin Bracey <kevin@bracey.fi> Reviewed-by: David Aguilar <davvid@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-03-13 01:12:21 +00:00
create_virtual_base::
modifies the first file so only lines in common with the
second file remain. If there is insufficient common material,
then the first file is left empty. The result is suitable
as a virtual base input for a 3-way merge.
GIT
---
Part of the linkgit:git[1] suite