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-rw-r--r--Documentation/git-update-ref.txt60
1 files changed, 59 insertions, 1 deletions
diff --git a/Documentation/git-update-ref.txt b/Documentation/git-update-ref.txt
index 0df13ff6f4..c8f5ae5cb3 100644
--- a/Documentation/git-update-ref.txt
+++ b/Documentation/git-update-ref.txt
@@ -8,7 +8,7 @@ git-update-ref - Update the object name stored in a ref safely
SYNOPSIS
--------
[verse]
-'git update-ref' [-m <reason>] (-d <ref> [<oldvalue>] | [--no-deref] <ref> <newvalue> [<oldvalue>])
+'git update-ref' [-m <reason>] (-d <ref> [<oldvalue>] | [--no-deref] <ref> <newvalue> [<oldvalue>] | --stdin [-z])
DESCRIPTION
-----------
@@ -58,6 +58,64 @@ archive by creating a symlink tree).
With `-d` flag, it deletes the named <ref> after verifying it
still contains <oldvalue>.
+With `--stdin`, update-ref reads instructions from standard input and
+performs all modifications together. Specify commands of the form:
+
+ update SP <ref> SP <newvalue> [SP <oldvalue>] LF
+ create SP <ref> SP <newvalue> LF
+ delete SP <ref> [SP <oldvalue>] LF
+ verify SP <ref> [SP <oldvalue>] LF
+ option SP <opt> LF
+
+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 <ref> NUL <newvalue> NUL [<oldvalue>] NUL
+ create SP <ref> NUL <newvalue> NUL
+ delete SP <ref> NUL [<oldvalue>] NUL
+ verify SP <ref> NUL [<oldvalue>] NUL
+ option SP <opt> 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 <ref> produce an error. Command meanings are:
+
+update::
+ Set <ref> to <newvalue> after verifying <oldvalue>, if given.
+ Specify a zero <newvalue> to ensure the ref does not exist
+ after the update and/or a zero <oldvalue> to make sure the
+ ref does not exist before the update.
+
+create::
+ Create <ref> with <newvalue> after verifying it does not
+ exist. The given <newvalue> may not be zero.
+
+delete::
+ Delete <ref> after verifying it exists with <oldvalue>, if
+ given. If given, <oldvalue> may not be zero.
+
+verify::
+ Verify <ref> against <oldvalue> but do not change it. If
+ <oldvalue> zero or missing, the ref must not exist.
+
+option::
+ Modify behavior of the next command naming a <ref>.
+ The only valid option is `no-deref` to avoid dereferencing
+ a symbolic ref.
+
+If all <ref>s can be locked with matching <oldvalue>s
+simultaneously, all modifications are performed. Otherwise, no
+modifications are performed. Note that while each individual
+<ref> is updated or deleted atomically, a concurrent reader may
+still see a subset of the modifications.
Logging Updates
---------------