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git-bisect
Langue: en
Version: 09/23/2007 (openSuse - 09/10/07)
Section: 1 (Commandes utilisateur)
Sommaire
NAME
git-bisect - Find the change that introduced a bug by binary searchSYNOPSIS
git bisect <subcommand> <options>DESCRIPTION
The command takes various subcommands, and different options depending on the subcommand:-
git bisect start [<bad> [<good>...]] [--] [<paths>...] git bisect bad <rev> git bisect good <rev> git bisect reset [<branch>] git bisect visualize git bisect replay <logfile> git bisect log git bisect run <cmd>...
Basic bisect commands: start, bad, good
The way you use it is:-
$ git bisect start $ git bisect bad # Current version is bad $ git bisect good v2.6.13-rc2 # v2.6.13-rc2 was the last version # tested that was good
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Bisecting: 675 revisions left to test after this
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$ git bisect good # this one is good
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Bisecting: 337 revisions left to test after this
Until you have no more left, and you'll have been left with the first bad kernel rev in "refs/bisect/bad".
Bisect reset
Oh, and then after you want to reset to the original head, do a-
$ git bisect reset
Bisect visualize
During the bisection process, you can say-
$ git bisect visualize
Bisect log and bisect replay
The good/bad input is logged, and-
$ git bisect log
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$ git bisect replay that-file
Avoiding to test a commit
If in a middle of bisect session, you know what the bisect suggested to try next is not a good one to test (e.g. the change the commit introduces is known not to work in your environment and you know it does not have anything to do with the bug you are chasing), you may want to find a near-by commit and try that instead.It goes something like this:
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$ git bisect good/bad # previous round was good/bad. Bisecting: 337 revisions left to test after this $ git bisect visualize # oops, that is uninteresting. $ git reset --hard HEAD~3 # try 3 revs before what # was suggested
Cutting down bisection by giving more parameters to bisect start
You can further cut down the number of trials if you know what part of the tree is involved in the problem you are tracking down, by giving paths parameters when you say bisect start, like this:-
$ git bisect start -- arch/i386 include/asm-i386
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$ git bisect start v2.6.20-rc6 v2.6.20-rc4 v2.6.20-rc1 -- # v2.6.20-rc6 is bad # v2.6.20-rc4 and v2.6.20-rc1 are good
Bisect run
If you have a script that can tell if the current source code is good or bad, you can automatically bisect using:-
$ git bisect run my_script
Any other exit code will abort the automatic bisect process. (A program that does "exit(-1)" leaves $? = 255, see exit(3) manual page, the value is chopped with "& 0377".)
You may often find that during bisect you want to have near-constant tweaks (e.g., s/#define DEBUG 0/#define DEBUG 1/ in a header file, or "revision that does not have this commit needs this patch applied to work around other problem this bisection is not interested in") applied to the revision being tested.
To cope with such a situation, after the inner git-bisect finds the next revision to test, with the "run" script, you can apply that tweak before compiling, run the real test, and after the test decides if the revision (possibly with the needed tweaks) passed the test, rewind the tree to the pristine state. Finally the "run" script can exit with the status of the real test to let "git bisect run" command loop to know the outcome.
AUTHOR
Written by Linus Torvalds <torvalds@osdl.org>DOCUMENTATION
Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.GIT
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