Merge branch 'bc/hash-independent-tests'
[git/git.git] / Documentation / git-receive-pack.txt
1 git-receive-pack(1)
2 ===================
3
4 NAME
5 ----
6 git-receive-pack - Receive what is pushed into the repository
7
8
9 SYNOPSIS
10 --------
11 [verse]
12 'git-receive-pack' <directory>
13
14 DESCRIPTION
15 -----------
16 Invoked by 'git send-pack' and updates the repository with the
17 information fed from the remote end.
18
19 This command is usually not invoked directly by the end user.
20 The UI for the protocol is on the 'git send-pack' side, and the
21 program pair is meant to be used to push updates to remote
22 repository. For pull operations, see linkgit:git-fetch-pack[1].
23
24 The command allows for creation and fast-forwarding of sha1 refs
25 (heads/tags) on the remote end (strictly speaking, it is the
26 local end 'git-receive-pack' runs, but to the user who is sitting at
27 the send-pack end, it is updating the remote. Confused?)
28
29 There are other real-world examples of using update and
30 post-update hooks found in the Documentation/howto directory.
31
32 'git-receive-pack' honours the receive.denyNonFastForwards config
33 option, which tells it if updates to a ref should be denied if they
34 are not fast-forwards.
35
36 A number of other receive.* config options are available to tweak
37 its behavior, see linkgit:git-config[1].
38
39 OPTIONS
40 -------
41 <directory>::
42 The repository to sync into.
43
44 PRE-RECEIVE HOOK
45 ----------------
46 Before any ref is updated, if $GIT_DIR/hooks/pre-receive file exists
47 and is executable, it will be invoked once with no parameters. The
48 standard input of the hook will be one line per ref to be updated:
49
50 sha1-old SP sha1-new SP refname LF
51
52 The refname value is relative to $GIT_DIR; e.g. for the master
53 head this is "refs/heads/master". The two sha1 values before
54 each refname are the object names for the refname before and after
55 the update. Refs to be created will have sha1-old equal to 0\{40},
56 while refs to be deleted will have sha1-new equal to 0\{40}, otherwise
57 sha1-old and sha1-new should be valid objects in the repository.
58
59 When accepting a signed push (see linkgit:git-push[1]), the signed
60 push certificate is stored in a blob and an environment variable
61 `GIT_PUSH_CERT` can be consulted for its object name. See the
62 description of `post-receive` hook for an example. In addition, the
63 certificate is verified using GPG and the result is exported with
64 the following environment variables:
65
66 `GIT_PUSH_CERT_SIGNER`::
67 The name and the e-mail address of the owner of the key that
68 signed the push certificate.
69
70 `GIT_PUSH_CERT_KEY`::
71 The GPG key ID of the key that signed the push certificate.
72
73 `GIT_PUSH_CERT_STATUS`::
74 The status of GPG verification of the push certificate,
75 using the same mnemonic as used in `%G?` format of `git log`
76 family of commands (see linkgit:git-log[1]).
77
78 `GIT_PUSH_CERT_NONCE`::
79 The nonce string the process asked the signer to include
80 in the push certificate. If this does not match the value
81 recorded on the "nonce" header in the push certificate, it
82 may indicate that the certificate is a valid one that is
83 being replayed from a separate "git push" session.
84
85 `GIT_PUSH_CERT_NONCE_STATUS`::
86 `UNSOLICITED`;;
87 "git push --signed" sent a nonce when we did not ask it to
88 send one.
89 `MISSING`;;
90 "git push --signed" did not send any nonce header.
91 `BAD`;;
92 "git push --signed" sent a bogus nonce.
93 `OK`;;
94 "git push --signed" sent the nonce we asked it to send.
95 `SLOP`;;
96 "git push --signed" sent a nonce different from what we
97 asked it to send now, but in a previous session. See
98 `GIT_PUSH_CERT_NONCE_SLOP` environment variable.
99
100 `GIT_PUSH_CERT_NONCE_SLOP`::
101 "git push --signed" sent a nonce different from what we
102 asked it to send now, but in a different session whose
103 starting time is different by this many seconds from the
104 current session. Only meaningful when
105 `GIT_PUSH_CERT_NONCE_STATUS` says `SLOP`.
106 Also read about `receive.certNonceSlop` variable in
107 linkgit:git-config[1].
108
109 This hook is called before any refname is updated and before any
110 fast-forward checks are performed.
111
112 If the pre-receive hook exits with a non-zero exit status no updates
113 will be performed, and the update, post-receive and post-update
114 hooks will not be invoked either. This can be useful to quickly
115 bail out if the update is not to be supported.
116
117 See the notes on the quarantine environment below.
118
119 UPDATE HOOK
120 -----------
121 Before each ref is updated, if $GIT_DIR/hooks/update file exists
122 and is executable, it is invoked once per ref, with three parameters:
123
124 $GIT_DIR/hooks/update refname sha1-old sha1-new
125
126 The refname parameter is relative to $GIT_DIR; e.g. for the master
127 head this is "refs/heads/master". The two sha1 arguments are
128 the object names for the refname before and after the update.
129 Note that the hook is called before the refname is updated,
130 so either sha1-old is 0\{40} (meaning there is no such ref yet),
131 or it should match what is recorded in refname.
132
133 The hook should exit with non-zero status if it wants to disallow
134 updating the named ref. Otherwise it should exit with zero.
135
136 Successful execution (a zero exit status) of this hook does not
137 ensure the ref will actually be updated, it is only a prerequisite.
138 As such it is not a good idea to send notices (e.g. email) from
139 this hook. Consider using the post-receive hook instead.
140
141 POST-RECEIVE HOOK
142 -----------------
143 After all refs were updated (or attempted to be updated), if any
144 ref update was successful, and if $GIT_DIR/hooks/post-receive
145 file exists and is executable, it will be invoked once with no
146 parameters. The standard input of the hook will be one line
147 for each successfully updated ref:
148
149 sha1-old SP sha1-new SP refname LF
150
151 The refname value is relative to $GIT_DIR; e.g. for the master
152 head this is "refs/heads/master". The two sha1 values before
153 each refname are the object names for the refname before and after
154 the update. Refs that were created will have sha1-old equal to
155 0\{40}, while refs that were deleted will have sha1-new equal to
156 0\{40}, otherwise sha1-old and sha1-new should be valid objects in
157 the repository.
158
159 The `GIT_PUSH_CERT*` environment variables can be inspected, just as
160 in `pre-receive` hook, after accepting a signed push.
161
162 Using this hook, it is easy to generate mails describing the updates
163 to the repository. This example script sends one mail message per
164 ref listing the commits pushed to the repository, and logs the push
165 certificates of signed pushes with good signatures to a logger
166 service:
167
168 #!/bin/sh
169 # mail out commit update information.
170 while read oval nval ref
171 do
172 if expr "$oval" : '0*$' >/dev/null
173 then
174 echo "Created a new ref, with the following commits:"
175 git rev-list --pretty "$nval"
176 else
177 echo "New commits:"
178 git rev-list --pretty "$nval" "^$oval"
179 fi |
180 mail -s "Changes to ref $ref" commit-list@mydomain
181 done
182 # log signed push certificate, if any
183 if test -n "${GIT_PUSH_CERT-}" && test ${GIT_PUSH_CERT_STATUS} = G
184 then
185 (
186 echo expected nonce is ${GIT_PUSH_NONCE}
187 git cat-file blob ${GIT_PUSH_CERT}
188 ) | mail -s "push certificate from $GIT_PUSH_CERT_SIGNER" push-log@mydomain
189 fi
190 exit 0
191
192 The exit code from this hook invocation is ignored, however a
193 non-zero exit code will generate an error message.
194
195 Note that it is possible for refname to not have sha1-new when this
196 hook runs. This can easily occur if another user modifies the ref
197 after it was updated by 'git-receive-pack', but before the hook was able
198 to evaluate it. It is recommended that hooks rely on sha1-new
199 rather than the current value of refname.
200
201 POST-UPDATE HOOK
202 ----------------
203 After all other processing, if at least one ref was updated, and
204 if $GIT_DIR/hooks/post-update file exists and is executable, then
205 post-update will be called with the list of refs that have been updated.
206 This can be used to implement any repository wide cleanup tasks.
207
208 The exit code from this hook invocation is ignored; the only thing
209 left for 'git-receive-pack' to do at that point is to exit itself
210 anyway.
211
212 This hook can be used, for example, to run `git update-server-info`
213 if the repository is packed and is served via a dumb transport.
214
215 #!/bin/sh
216 exec git update-server-info
217
218
219 QUARANTINE ENVIRONMENT
220 ----------------------
221
222 When `receive-pack` takes in objects, they are placed into a temporary
223 "quarantine" directory within the `$GIT_DIR/objects` directory and
224 migrated into the main object store only after the `pre-receive` hook
225 has completed. If the push fails before then, the temporary directory is
226 removed entirely.
227
228 This has a few user-visible effects and caveats:
229
230 1. Pushes which fail due to problems with the incoming pack, missing
231 objects, or due to the `pre-receive` hook will not leave any
232 on-disk data. This is usually helpful to prevent repeated failed
233 pushes from filling up your disk, but can make debugging more
234 challenging.
235
236 2. Any objects created by the `pre-receive` hook will be created in
237 the quarantine directory (and migrated only if it succeeds).
238
239 3. The `pre-receive` hook MUST NOT update any refs to point to
240 quarantined objects. Other programs accessing the repository will
241 not be able to see the objects (and if the pre-receive hook fails,
242 those refs would become corrupted). For safety, any ref updates
243 from within `pre-receive` are automatically rejected.
244
245
246 SEE ALSO
247 --------
248 linkgit:git-send-pack[1], linkgit:gitnamespaces[7]
249
250 GIT
251 ---
252 Part of the linkgit:git[1] suite