Junio C Hamano
19 years ago
27 changed files with 241 additions and 148 deletions
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git-symbolic-ref(1) |
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=================== |
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NAME |
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---- |
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git-symbolic-ref - read and modify symbolic refs |
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SYNOPSIS |
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-------- |
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'git-symbolic-ref' <name> [<ref>] |
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DESCRIPTION |
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----------- |
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Given one argument, reads which branch head the given symbolic |
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ref refers to and outputs its path, relative to the `.git/` |
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directory. Typically you would give `HEAD` as the <name> |
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argument to see on which branch your working tree is on. |
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Give two arguments, create or update a symbolic ref <name> to |
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point at the given branch <ref>. |
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Traditionally, `.git/HEAD` is a symlink pointing at |
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`refs/heads/master`. When we want to switch to another branch, |
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we did `ln -sf refs/heads/newbranch .git/HEAD`, and when we want |
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to find out which branch we are on, we did `readlink .git/HEAD`. |
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This was fine, and internally that is what still happens by |
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default, but on platforms that does not have working symlinks, |
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or that does not have the `readlink(1)` command, this was a bit |
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cumbersome. On some platforms, `ln -sf` does not even work as |
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advertised (horrors). |
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A symbolic ref can be a regular file that stores a string that |
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begins with `ref: refs/`. For example, your `.git/HEAD` *can* |
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be a regular file whose contents is `ref: refs/heads/master`. |
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This can be used on a filesystem that does not support symbolic |
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links. Instead of doing `readlink .git/HEAD`, `git-symbolic-ref |
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HEAD` can be used to find out which branch we are on. To point |
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the HEAD to `newbranch`, instead of `ln -sf refs/heads/newbranch |
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.git/HEAD`, `git-symbolic-ref HEAD refs/heads/newbranch` can be |
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used. |
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Currently, .git/HEAD uses a regular file symbolic ref on Cygwin, |
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and everywhere else it is implemented as a symlink. This can be |
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changed at compilation time. |
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Author |
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------ |
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Written by Junio C Hamano <junkio@cox.net> |
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GIT |
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--- |
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Part of the gitlink:git[7] suite |
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git-update-ref(1) |
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================= |
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NAME |
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---- |
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git-update-ref - update the object name stored in a ref safely |
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SYNOPSIS |
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-------- |
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`git-update-ref` <ref> <newvalue> [<oldvalue>] |
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DESCRIPTION |
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----------- |
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Given two arguments, stores the <newvalue> in the <ref>, possibly |
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dereferencing the symbolic refs. E.g. `git-update-ref HEAD |
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<newvalue>` updates the current branch head to the new object. |
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Given three arguments, stores the <newvalue> in the <ref>, |
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possibly dereferencing the symbolic refs, after verifying that |
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the current value of the <ref> matches <oldvalue>. |
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E.g. `git-update-ref refs/heads/master <newvalue> <oldvalue>` |
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updates the master branch head to <newvalue> only if its current |
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value is <oldvalue>. |
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It also allows a "ref" file to be a symbolic pointer to another |
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ref file by starting with the four-byte header sequence of |
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"ref:". |
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More importantly, it allows the update of a ref file to follow |
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these symbolic pointers, whether they are symlinks or these |
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"regular file symbolic refs". It follows *real* symlinks only |
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if they start with "refs/": otherwise it will just try to read |
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them and update them as a regular file (i.e. it will allow the |
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filesystem to follow them, but will overwrite such a symlink to |
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somewhere else with a regular filename). |
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In general, using |
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git-update-ref HEAD "$head" |
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should be a _lot_ safer than doing |
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echo "$head" > "$GIT_DIR/HEAD" |
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both from a symlink following standpoint *and* an error checking |
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standpoint. The "refs/" rule for symlinks means that symlinks |
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that point to "outside" the tree are safe: they'll be followed |
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for reading but not for writing (so we'll never write through a |
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ref symlink to some other tree, if you have copied a whole |
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archive by creating a symlink tree). |
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Author |
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------ |
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Written by Linus Torvalds <torvalds@osdl.org>. |
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GIT |
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--- |
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Part of the gitlink:git[7] suite |
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@ -1,67 +0,0 @@
@@ -1,67 +0,0 @@
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#!/bin/sh |
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# Copyright (C) 2005 Junio C Hamano |
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# |
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# This script is designed to emulate what the built-in diff driver |
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# does when set as GIT_EXTERNAL_SCRIPT. |
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case "$#" in |
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1) |
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echo "* Unmerged path $1" |
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exit 0 ;; |
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*) |
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name1="$1" tmp1="$2" hex1="$3" mode1="$4" tmp2="$5" hex2="$6" mode2="$7" |
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case "$#" in |
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7) |
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name2="$name1" ;; |
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9) |
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name2="$8" xfrm_msg="$9" ;; |
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esac ;; |
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esac |
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show_create () { |
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name_="$1" tmp_="$2" hex_="$3" mode_="$4" |
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echo "diff --git a/$name_ b/$name_" |
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echo "new file mode $mode_" |
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diff ${GIT_DIFF_OPTS-'-pu'} -L /dev/null -L "b/$name_" /dev/null "$tmp_" |
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} |
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show_delete () { |
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name_="$1" tmp_="$2" hex_="$3" mode_="$4" |
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echo "diff --git a/$name_ b/$name_" |
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echo "deleted file mode $mode_" |
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diff ${GIT_DIFF_OPTS-'-pu'} -L "a/$name_" -L /dev/null "$tmp_" /dev/null |
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} |
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case "$mode1" in |
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120*) type1=l ;; |
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100*) type1=f ;; |
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.) show_create "$name2" "$tmp2" "$hex2" "$mode2" |
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exit 0 ;; |
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esac |
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case "$mode2" in |
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120*) type2=l ;; |
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100*) type2=f ;; |
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.) show_delete "$name1" "$tmp1" "$hex1" "$mode1" |
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exit 0 ;; |
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esac |
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if test "$type1" != "$type2" |
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then |
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show_delete "$name1" "$tmp1" "$hex1" "$mode1" |
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show_create "$name2" "$tmp2" "$hex2" "$mode2" |
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exit 0 |
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fi |
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echo diff --git "a/$name1" "b/$name2" |
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if test "$mode1" != "$mode2" |
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then |
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echo "old mode $mode1" |
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echo "new mode $mode2" |
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if test "$xfrm_msg" != "" |
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then |
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echo "$xfrm_msg" |
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fi |
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fi |
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diff ${GIT_DIFF_OPTS-'-pu'} -L "a/$name1" -L "b/$name2" "$tmp1" "$tmp2" |
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exit 0 |
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