-
Notifications
You must be signed in to change notification settings - Fork 0
/
git-update-ref.txt
205 lines (162 loc) · 7.09 KB
/
git-update-ref.txt
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
git-update-ref(1)
=================
NAME
----
git-update-ref - Update the object name stored in a ref safely
SYNOPSIS
--------
[verse]
'git update-ref' [-m <reason>] [--no-deref] (-d <ref> [<old-oid>] | [--create-reflog] <ref> <new-oid> [<old-oid>] | --stdin [-z])
DESCRIPTION
-----------
Given two arguments, stores the <new-oid> in the <ref>, possibly
dereferencing the symbolic refs. E.g. `git update-ref HEAD
<new-oid>` updates the current branch head to the new object.
Given three arguments, stores the <new-oid> in the <ref>,
possibly dereferencing the symbolic refs, after verifying that
the current value of the <ref> matches <old-oid>.
E.g. `git update-ref refs/heads/master <new-oid> <old-oid>`
updates the master branch head to <new-oid> only if its current
value is <old-oid>. You can specify 40 "0" or an empty string
as <old-oid> 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, <ref> 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 <ref> after verifying it
still contains <old-oid>.
With `--stdin`, update-ref reads instructions from standard input and
performs all modifications together. Specify commands of the form:
update SP <ref> SP <new-oid> [SP <old-oid>] LF
create SP <ref> SP <new-oid> LF
delete SP <ref> [SP <old-oid>] LF
verify SP <ref> [SP <old-oid>] LF
symref-update SP <ref> SP <new-target> [SP (ref SP <old-target> | oid SP <old-oid>)] LF
symref-create SP <ref> SP <new-target> LF
symref-delete SP <ref> [SP <old-target>] LF
symref-verify SP <ref> [SP <old-target>] LF
option SP <opt> 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 <ref> NUL <new-oid> NUL [<old-oid>] NUL
create SP <ref> NUL <new-oid> NUL
delete SP <ref> NUL [<old-oid>] NUL
verify SP <ref> NUL [<old-oid>] NUL
symref-update SP <ref> NUL <new-target> [NUL (ref NUL <old-target> | oid NUL <old-oid>)] NUL
symref-create SP <ref> NUL <new-target> NUL
symref-delete SP <ref> [NUL <old-target>] NUL
symref-verify SP <ref> [NUL <old-target>] NUL
option SP <opt> 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 <ref> produce an error. Command meanings are:
update::
Set <ref> to <new-oid> after verifying <old-oid>, if given.
Specify a zero <new-oid> to ensure the ref does not exist
after the update and/or a zero <old-oid> to make sure the
ref does not exist before the update.
create::
Create <ref> with <new-oid> after verifying it does not
exist. The given <new-oid> may not be zero.
delete::
Delete <ref> after verifying it exists with <old-oid>, if
given. If given, <old-oid> may not be zero.
symref-update::
Set <ref> to <new-target> after verifying <old-target> or <old-oid>,
if given. Specify a zero <old-oid> to ensure that the ref does not
exist before the update.
verify::
Verify <ref> against <old-oid> but do not change it. If
<old-oid> is zero or missing, the ref must not exist.
symref-create:
Create symbolic ref <ref> with <new-target> after verifying
it does not exist.
symref-delete::
Delete <ref> after verifying it exists with <old-target>, if given.
symref-verify::
Verify symbolic <ref> against <old-target> but do not change it.
If <old-target> is missing, the ref must not exist. Can only be
used in `no-deref` mode.
option::
Modify the behavior of the next command naming a <ref>.
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 <ref>s can be locked with matching <old-oid>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
---------------
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/<ref>" exists then
`git update-ref` will append a line to the log file
"$GIT_DIR/logs/<ref>" (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 <ref>, "newsha1" is the 40 character hexadecimal value of
<new-oid> 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 <ref>) 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