1GIT-BISECT(1) Git Manual GIT-BISECT(1)
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6 git-bisect - Find by binary search the change that introduced a bug
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9 git bisect <subcommand> <options>
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12 The command takes various subcommands, and different options depending
13 on the subcommand:
14 git bisect help
16 git bisect start [<bad> [<good>...]] [--] [<paths>...]
17 git bisect bad [<rev>]
18 git bisect good [<rev>...]
19 git bisect skip [(<rev>|<range>)...]
20 git bisect reset [<commit>]
21 git bisect visualize
22 git bisect replay <logfile>
23 git bisect log
24 git bisect run <cmd>...
25 This command uses git rev-list --bisect to help drive the binary search
27 process to find which change introduced a bug, given an old "good"
28 commit object name and a later "bad" commit object name.
29 Getting help
31 Use "git bisect" to get a short usage description, and "git bisect
32 help" or "git bisect -h" to get a long usage description.
33 Basic bisect commands: start, bad, good
35 Using the Linux kernel tree as an example, basic use of the bisect
36 command is as follows:
37 $ git bisect start
39 $ git bisect bad # Current version is bad
40 $ git bisect good v2.6.13-rc2 # v2.6.13-rc2 was the last version
41 # tested that was good
42 When you have specified at least one bad and one good version, the
45 command bisects the revision tree and outputs something similar to the
46 following:
47 Bisecting: 675 revisions left to test after this
49 The state in the middle of the set of revisions is then checked out.
52 You would now compile that kernel and boot it. If the booted kernel
53 works correctly, you would then issue the following command:
54 $ git bisect good # this one is good
56 The output of this command would be something similar to the following:
59 Bisecting: 337 revisions left to test after this
61 You keep repeating this process, compiling the tree, testing it, and
64 depending on whether it is good or bad issuing the command "git bisect
65 good" or "git bisect bad" to ask for the next bisection.
66 Eventually there will be no more revisions left to bisect, and you will
68 have been left with the first bad kernel revision in "refs/bisect/bad".
69 Bisect reset
71 After a bisect session, to clean up the bisection state and return to
72 the original HEAD, issue the following command:
73 $ git bisect reset
75 By default, this will return your tree to the commit that was checked
78 out before git bisect start. (A new git bisect start will also do that,
79 as it cleans up the old bisection state.)
80 With an optional argument, you can return to a different commit
82 instead:
83 $ git bisect reset <commit>
85 For example, git bisect reset HEAD will leave you on the current
88 bisection commit and avoid switching commits at all, while git bisect
89 reset bisect/bad will check out the first bad revision.
90 Bisect visualize
92 To see the currently remaining suspects in gitk, issue the following
93 command during the bisection process:
94 $ git bisect visualize
96 view may also be used as a synonym for visualize.
99 If the DISPLAY environment variable is not set, git log is used
101 instead. You can also give command line options such as -p and --stat.
102 $ git bisect view --stat
104 Bisect log and bisect replay
107 After having marked revisions as good or bad, issue the following
108 command to show what has been done so far:
109 $ git bisect log
111 If you discover that you made a mistake in specifying the status of a
114 revision, you can save the output of this command to a file, edit it to
115 remove the incorrect entries, and then issue the following commands to
116 return to a corrected state:
117 $ git bisect reset
119 $ git bisect replay that-file
120 Avoiding testing a commit
123 If, in the middle of a bisect session, you know that the next suggested
124 revision is not a good one to test (e.g. the change the commit
125 introduces is known not to work in your environment and you know it
126 does not have anything to do with the bug you are chasing), you may
127 want to find a nearby commit and try that instead.
128 For example:
130 $ git bisect good/bad # previous round was good or bad.
132 Bisecting: 337 revisions left to test after this
133 $ git bisect visualize # oops, that is uninteresting.
134 $ git reset --hard HEAD~3 # try 3 revisions before what
135 # was suggested
136 Then compile and test the chosen revision, and afterwards mark the
139 revision as good or bad in the usual manner.
140 Bisect skip
142 Instead of choosing by yourself a nearby commit, you can ask git to do
143 it for you by issuing the command:
144 $ git bisect skip # Current version cannot be tested
146 But git may eventually be unable to tell the first bad commit among a
149 bad commit and one or more skipped commits.
150 You can even skip a range of commits, instead of just one commit, using
152 the "<commit1>..<commit2>" notation. For example:
153 $ git bisect skip v2.5..v2.6
155 This tells the bisect process that no commit after v2.5, up to and
158 including v2.6, should be tested.
159 Note that if you also want to skip the first commit of the range you
161 would issue the command:
162 $ git bisect skip v2.5 v2.5..v2.6
164 This tells the bisect process that the commits between v2.5 included
167 and v2.6 included should be skipped.
168 Cutting down bisection by giving more parameters to bisect start
170 You can further cut down the number of trials, if you know what part of
171 the tree is involved in the problem you are tracking down, by
172 specifying path parameters when issuing the bisect start command:
173 $ git bisect start -- arch/i386 include/asm-i386
175 If you know beforehand more than one good commit, you can narrow the
178 bisect space down by specifying all of the good commits immediately
179 after the bad commit when issuing the bisect start command:
180 $ git bisect start v2.6.20-rc6 v2.6.20-rc4 v2.6.20-rc1 --
182 # v2.6.20-rc6 is bad
183 # v2.6.20-rc4 and v2.6.20-rc1 are good
184 Bisect run
187 If you have a script that can tell if the current source code is good
188 or bad, you can bisect by issuing the command:
189 $ git bisect run my_script arguments
191 Note that the script (my_script in the above example) should exit with
194 code 0 if the current source code is good, and exit with a code between
195 1 and 127 (inclusive), except 125, if the current source code is bad.
196 Any other exit code will abort the bisect process. It should be noted
198 that a program that terminates via "exit(-1)" leaves $? = 255, (see the
199 exit(3) manual page), as the value is chopped with "& 0377".
200 The special exit code 125 should be used when the current source code
202 cannot be tested. If the script exits with this code, the current
203 revision will be skipped (see git bisect skip above).
204 You may often find that during a bisect session you want to have
206 temporary modifications (e.g. s/#define DEBUG 0/#define DEBUG 1/ in a
207 header file, or "revision that does not have this commit needs this
208 patch applied to work around another problem this bisection is not
209 interested in") applied to the revision being tested.
210 To cope with such a situation, after the inner git bisect finds the
212 next revision to test, the script can apply the patch before compiling,
213 run the real test, and afterwards decide if the revision (possibly with
214 the needed patch) passed the test and then rewind the tree to the
215 pristine state. Finally the script should exit with the status of the
216 real test to let the "git bisect run" command loop determine the
217 eventual outcome of the bisect session.
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220 · Automatically bisect a broken build between v1.2 and HEAD:
221 $ git bisect start HEAD v1.2 -- # HEAD is bad, v1.2 is good
223 $ git bisect run make # "make" builds the app
224 · Automatically bisect a test failure between origin and HEAD:
227 $ git bisect start HEAD origin -- # HEAD is bad, origin is good
229 $ git bisect run make test # "make test" builds and tests
230 · Automatically bisect a broken test suite:
233 $ cat ~/test.sh
235 #!/bin/sh
236 make || exit 125 # this skips broken builds
237 make test # "make test" runs the test suite
238 $ git bisect start v1.3 v1.1 -- # v1.3 is bad, v1.1 is good
239 $ git bisect run ~/test.sh
240 Here we use a "test.sh" custom script. In this script, if "make"
242 fails, we skip the current commit.
243 It is safer to use a custom script outside the repository to
245 prevent interactions between the bisect, make and test processes
246 and the script.
247 "make test" should "exit 0", if the test suite passes, and "exit 1"
249 otherwise.
250 · Automatically bisect a broken test case:
252 $ cat ~/test.sh
254 #!/bin/sh
255 make || exit 125 # this skips broken builds
256 ~/check_test_case.sh # does the test case passes ?
257 $ git bisect start HEAD HEAD~10 -- # culprit is among the last 10
258 $ git bisect run ~/test.sh
259 Here "check_test_case.sh" should "exit 0" if the test case passes,
261 and "exit 1" otherwise.
262 It is safer if both "test.sh" and "check_test_case.sh" scripts are
264 outside the repository to prevent interactions between the bisect,
265 make and test processes and the scripts.
266 · Automatically bisect a broken test suite:
268 $ git bisect start HEAD HEAD~10 -- # culprit is among the last 10
270 $ git bisect run sh -c "make || exit 125; ~/check_test_case.sh"
271 Does the same as the previous example, but on a single line.
273
275 Written by Linus Torvalds <torvalds@osdl.org[1]>
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278 Documentation by Junio C Hamano and the git-list
279 <git@vger.kernel.org[2]>.
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282 Fighting regressions with git bisect[3], git-blame(1).
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285 Part of the git(1) suite
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288 1. torvalds@osdl.org
289 mailto:torvalds@osdl.org
290 2. git@vger.kernel.org
292 mailto:git@vger.kernel.org
293 3. Fighting regressions with git bisect
295 file:///usr/share/doc/git-1.7.1/git-bisect-lk2009.html
296Git 1.7.1 08/16/2017 GIT-BISECT(1)