SYNOPSIS
--------
-'git bisect' <subcommand> <options>
+'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>
+The command takes various subcommands, and different options depending
+on the subcommand:
+
+ git bisect help
+ git bisect start [<bad> [<good>...]] [--] [<paths>...]
+ git bisect bad [<rev>]
+ git bisect good [<rev>...]
+ git bisect skip [<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.
+
+Getting help
+~~~~~~~~~~~~
-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.
+Use "git bisect" to get a short usage description, and "git bisect
+help" or "git bisect -h" to get a long usage description.
+
+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
+$ 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:
+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
+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
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.
+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".
-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).
+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`.
+to see the currently remaining suspects in `gitk`. `visualize` is a bit
+too long to type and `view` is provided as a synonym.
-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
+If `DISPLAY` environment variable is not set, `git log` is used
+instead. You can even give command line options such as `-p` and
+`--stat`.
+
+------------
+$ git bisect view --stat
+------------
+
+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.
-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:
+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.
# was suggested
------------
-Then compile and test the one you chose to try. After that,
-tell bisect what the result was as usual.
+Then compile and test the one you chose to try. After that, tell
+bisect what the result was as usual.
-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:
+Bisect skip
+~~~~~~~~~~~~
+
+Instead of choosing by yourself a nearby commit, you may just want git
+to do it for you using:
------------
-$ git bisect start arch/i386 include/asm-i386
+$ git bisect skip # Current version cannot be tested
------------
+But computing the commit to test may be slower afterwards and git may
+eventually not be able to tell the first bad among a bad and one or
+more "skip"ped commits.
+
+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
+------------
+
+If you know beforehand more than one good commits, you can narrow the
+bisect space down without doing the whole tree checkout every time you
+give good commits. You give the bad revision immediately after `start`
+and then you give all the good revisions you have:
+
+------------
+$ 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
+------------
+
+Note that the "run" script (`my_script` in the above example) should
+exit with code 0 in case the current source code is good. Exit with a
+code between 1 and 127 (inclusive), except 125, if 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".)
+
+The special exit code 125 should be used when the current source code
+cannot be tested. If the "run" script exits with this code, the current
+revision will be skipped, see `git bisect skip` above.
+
+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
------
GIT
---
-Part of the gitlink:git[7] suite
-
+Part of the linkgit:git[7] suite