mirror of
https://github.com/git/git
synced 2024-10-30 23:05:50 +00:00
6cea055547
Signed-off-by: Christian Couder <chriscool@tuxfamily.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
192 lines
5.7 KiB
Text
192 lines
5.7 KiB
Text
git-bisect(1)
|
|
=============
|
|
|
|
NAME
|
|
----
|
|
git-bisect - Find the change that introduced a bug by binary search
|
|
|
|
|
|
SYNOPSIS
|
|
--------
|
|
'git bisect' <subcommand> <options>
|
|
|
|
DESCRIPTION
|
|
-----------
|
|
The command takes various subcommands, and different options depending
|
|
on the subcommand:
|
|
|
|
git bisect start [<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>...
|
|
|
|
This command uses 'git-rev-list --bisect' option to help drive the
|
|
binary search process to find which change introduced a bug, given an
|
|
old "good" commit object name and a later "bad" commit object name.
|
|
|
|
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
|
|
------------------------------------------------
|
|
|
|
When you give at least one bad and one good versions, it will bisect
|
|
the revision tree and say something like:
|
|
|
|
------------------------------------------------
|
|
Bisecting: 675 revisions left to test after this
|
|
------------------------------------------------
|
|
|
|
and check out the state in the middle. Now, compile that kernel, and
|
|
boot it. Now, let's say that this booted kernel works fine, then just
|
|
do
|
|
|
|
------------------------------------------------
|
|
$ git bisect good # this one is good
|
|
------------------------------------------------
|
|
|
|
which will now say
|
|
|
|
------------------------------------------------
|
|
Bisecting: 337 revisions left to test after this
|
|
------------------------------------------------
|
|
|
|
and you continue along, compiling that one, testing it, and depending
|
|
on whether it is good or bad, you say "git bisect good" or "git bisect
|
|
bad", and ask for the next bisection.
|
|
|
|
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
|
|
------------------------------------------------
|
|
|
|
to get back to the master branch, instead of being in one of the
|
|
bisection branches ("git bisect start" will do that for you too,
|
|
actually: it will reset the bisection state, and before it does that
|
|
it checks that you're not using some old bisection branch).
|
|
|
|
Bisect visualize
|
|
~~~~~~~~~~~~~~~~
|
|
|
|
During the bisection process, you can say
|
|
|
|
------------
|
|
$ git bisect visualize
|
|
------------
|
|
|
|
to see the currently remaining suspects in `gitk`.
|
|
|
|
Bisect log and bisect replay
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
The good/bad input is logged, and
|
|
|
|
------------
|
|
$ git bisect log
|
|
------------
|
|
|
|
shows what you have done so far. You can truncate its output somewhere
|
|
and save it in a file, and run
|
|
|
|
------------
|
|
$ git bisect replay that-file
|
|
------------
|
|
|
|
if you find later you made a mistake telling good/bad about a
|
|
revision.
|
|
|
|
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:
|
|
|
|
------------
|
|
$ 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
|
|
------------
|
|
|
|
Then compile and test the one you chose to try. After that, tell
|
|
bisect what the result was as usual.
|
|
|
|
Cutting down bisection by giving path parameter 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
|
|
------------
|
|
|
|
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
|
|
------------
|
|
|
|
Note that the "run" script (`my_script` in the above example) should
|
|
exit with code 0 in case the current source code is good and with a
|
|
code between 1 and 127 (included) in case the current source code is
|
|
bad.
|
|
|
|
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
|
|
---
|
|
Part of the gitlink:git[7] suite
|
|
|