From c8bae7493d2f2910b57f13ded012e86bdcfb0532 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 16:47:53 +0200 Subject: Adding upstream version 1:2.39.2. Signed-off-by: Daniel Baumann --- Documentation/git-update-ref.txt | 180 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 180 insertions(+) create mode 100644 Documentation/git-update-ref.txt (limited to 'Documentation/git-update-ref.txt') diff --git a/Documentation/git-update-ref.txt b/Documentation/git-update-ref.txt new file mode 100644 index 0000000..48b6683 --- /dev/null +++ b/Documentation/git-update-ref.txt @@ -0,0 +1,180 @@ +git-update-ref(1) +================= + +NAME +---- +git-update-ref - Update the object name stored in a ref safely + +SYNOPSIS +-------- +[verse] +'git update-ref' [-m ] [--no-deref] (-d [] | [--create-reflog] [] | --stdin [-z]) + +DESCRIPTION +----------- +Given two arguments, stores the in the , possibly +dereferencing the symbolic refs. E.g. `git update-ref HEAD +` updates the current branch head to the new object. + +Given three arguments, stores the in the , +possibly dereferencing the symbolic refs, after verifying that +the current value of the matches . +E.g. `git update-ref refs/heads/master ` +updates the master branch head to only if its current +value is . You can specify 40 "0" or an empty string +as to make sure that the ref you are creating does +not exist. + +It also allows a "ref" file to be a symbolic pointer to another +ref file by starting with the four-byte header sequence of +"ref:". + +More importantly, it allows the update of a ref file to follow +these symbolic pointers, whether they are symlinks or these +"regular file symbolic refs". It follows *real* symlinks only +if they start with "refs/": otherwise it will just try to read +them and update them as a regular file (i.e. it will allow the +filesystem to follow them, but will overwrite such a symlink to +somewhere else with a regular filename). + +If --no-deref is given, itself is overwritten, rather than +the result of following the symbolic pointers. + +In general, using + + git update-ref HEAD "$head" + +should be a _lot_ safer than doing + + echo "$head" > "$GIT_DIR/HEAD" + +both from a symlink following standpoint *and* an error checking +standpoint. The "refs/" rule for symlinks means that symlinks +that point to "outside" the tree are safe: they'll be followed +for reading but not for writing (so we'll never write through a +ref symlink to some other tree, if you have copied a whole +archive by creating a symlink tree). + +With `-d` flag, it deletes the named after verifying it +still contains . + +With `--stdin`, update-ref reads instructions from standard input and +performs all modifications together. Specify commands of the form: + + update SP SP [SP ] LF + create SP SP LF + delete SP [SP ] LF + verify SP [SP ] LF + option SP LF + start LF + prepare LF + commit LF + abort LF + +With `--create-reflog`, update-ref will create a reflog for each ref +even if one would not ordinarily be created. + +Quote fields containing whitespace as if they were strings in C source +code; i.e., surrounded by double-quotes and with backslash escapes. +Use 40 "0" characters or the empty string to specify a zero value. To +specify a missing value, omit the value and its preceding SP entirely. + +Alternatively, use `-z` to specify in NUL-terminated format, without +quoting: + + update SP NUL NUL [] NUL + create SP NUL NUL + delete SP NUL [] NUL + verify SP NUL [] NUL + option SP NUL + start NUL + prepare NUL + commit NUL + abort NUL + +In this format, use 40 "0" to specify a zero value, and use the empty +string to specify a missing value. + +In either format, values can be specified in any form that Git +recognizes as an object name. Commands in any other format or a +repeated produce an error. Command meanings are: + +update:: + Set to after verifying , if given. + Specify a zero to ensure the ref does not exist + after the update and/or a zero to make sure the + ref does not exist before the update. + +create:: + Create with after verifying it does not + exist. The given may not be zero. + +delete:: + Delete after verifying it exists with , if + given. If given, may not be zero. + +verify:: + Verify against but do not change it. If + is zero or missing, the ref must not exist. + +option:: + Modify behavior of the next command naming a . + The only valid option is `no-deref` to avoid dereferencing + a symbolic ref. + +start:: + Start a transaction. In contrast to a non-transactional session, a + transaction will automatically abort if the session ends without an + explicit commit. This command may create a new empty transaction when + the current one has been committed or aborted already. + +prepare:: + Prepare to commit the transaction. This will create lock files for all + queued reference updates. If one reference could not be locked, the + transaction will be aborted. + +commit:: + Commit all reference updates queued for the transaction, ending the + transaction. + +abort:: + Abort the transaction, releasing all locks if the transaction is in + prepared state. + +If all s can be locked with matching s +simultaneously, all modifications are performed. Otherwise, no +modifications are performed. Note that while each individual + is updated or deleted atomically, a concurrent reader may +still see a subset of the modifications. + +LOGGING UPDATES +--------------- +If config parameter "core.logAllRefUpdates" is true and the ref is one +under "refs/heads/", "refs/remotes/", "refs/notes/", or a pseudoref +like HEAD or ORIG_HEAD; or the file "$GIT_DIR/logs/" exists then +`git update-ref` will append a line to the log file +"$GIT_DIR/logs/" (dereferencing all symbolic refs before creating +the log name) describing the change in ref value. Log lines are +formatted as: + + oldsha1 SP newsha1 SP committer LF + +Where "oldsha1" is the 40 character hexadecimal value previously +stored in , "newsha1" is the 40 character hexadecimal value of + and "committer" is the committer's name, email address +and date in the standard Git committer ident format. + +Optionally with -m: + + oldsha1 SP newsha1 SP committer TAB message LF + +Where all fields are as described above and "message" is the +value supplied to the -m option. + +An update will fail (without changing ) if the current user is +unable to create a new log file, append to the existing log file +or does not have committer information available. + +GIT +--- +Part of the linkgit:git[1] suite -- cgit v1.2.3