git bisect bad [<rev>]
git bisect good [<rev>...]
git bisect skip [(<rev>|<range>)...]
- git bisect reset [<branch>]
+ git bisect reset [<commit>]
git bisect visualize
git bisect replay <logfile>
git bisect log
Bisect reset
~~~~~~~~~~~~
-To return to the original head after a bisect session, you issue the
-following command:
+After a bisect session, to clean up the bisection state and return to
+the original HEAD, issue the following command:
------------------------------------------------
$ git bisect reset
------------------------------------------------
-This resets the tree to the original branch instead of being on the
-bisection commit ("git bisect start" will also do that, as it resets
-the bisection state).
+By default, this will return your tree to the commit that was checked
+out before `git bisect start`. (A new `git bisect start` will also do
+that, as it cleans up the old bisection state.)
+
+With an optional argument, you can return to a different commit
+instead:
+
+------------------------------------------------
+$ git bisect reset <commit>
+------------------------------------------------
+
+For example, `git bisect reset HEAD` will leave you on the current
+bisection commit and avoid switching commits at all, while `git bisect
+reset bisect/bad` will check out the first bad revision.
Bisect visualize
~~~~~~~~~~~~~~~~
-To see the currently remaining suspects in 'gitk', the following command
-is issued during the bisection process:
+To see the currently remaining suspects in 'gitk', issue the following
+command during the bisection process:
------------
$ git bisect visualize
Bisect log and bisect replay
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-After having marked revisions as good or bad, you issue the following
+After having marked revisions as good or bad, issue the following
command to show what has been done so far:
------------
Avoiding testing a commit
~~~~~~~~~~~~~~~~~~~~~~~~~
-If in the middle of a bisect session, you know that the next suggested
+If, in the middle of a bisect session, you know that the next suggested
revision 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
# was suggested
------------
-Then compile and test the chosen revision. Afterwards the revision
-is marked as good or bad in the usual manner.
+Then compile and test the chosen revision, and afterwards mark
+the revision as good or bad in the usual manner.
Bisect skip
~~~~~~~~~~~~
$ 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 commit among a bad commit
-and one or more skipped commits.
+But git may eventually be unable to tell the first bad commit among
+a bad commit and one or more skipped commits.
You can even skip a range of commits, instead of just one commit,
using the "'<commit1>'..'<commit2>'" notation. For example:
$ git bisect skip v2.5..v2.6
------------
-The effect of this would be that no commit between `v2.5` excluded and
-`v2.6` included could be tested.
+This tells the bisect process that no commit after `v2.5`, up to and
+including `v2.6`, should be tested.
Note that if you also want to skip the first commit of the range you
would issue the command:
$ git bisect skip v2.5 v2.5..v2.6
------------
-This would cause the commits between `v2.5` included and `v2.6` included
-to be skipped.
+This tells the bisect process that the commits between `v2.5` included
+and `v2.6` included should be skipped.
Cutting down bisection by giving more parameters to bisect start
or bad, you can bisect by issuing the command:
------------
-$ git bisect run my_script
+$ git bisect run my_script arguments
------------
Note that the script (`my_script` in the above example) should
The special exit code 125 should be used when the current source code
cannot be tested. If the script exits with this code, the current
-revision will be skipped (see `git bisect skip` above).
+revision will be skipped (see `git bisect skip` above). 125 was chosen
+as the highest sensible value to use for this purpose, because 126 and 127
+are used by POSIX shells to signal specific error status (127 is for
+command not found, 126 is for command found but not executable---these
+details do not matter, as they are normal errors in the script, as far as
+"bisect run" is concerned).
You may often find that during a bisect session you want to have
temporary modifications (e.g. s/#define DEBUG 0/#define DEBUG 1/ in a
$ git bisect run make # "make" builds the app
------------
-* Automatically bisect a broken test suite:
+* Automatically bisect a test failure between origin and HEAD:
+
------------
-$ cat ~/test.sh
-#!/bin/sh
-make || exit 125 # this skips broken builds
-make test # "make test" runs the test suite
-$ git bisect start v1.3 v1.1 -- # v1.3 is bad, v1.1 is good
-$ git bisect run ~/test.sh
+$ git bisect start HEAD origin -- # HEAD is bad, origin is good
+$ git bisect run make test # "make test" builds and tests
------------
-+
-Here we use a "test.sh" custom script. In this script, if "make"
-fails, we skip the current commit.
-+
-It is safer to use a custom script outside the repository to prevent
-interactions between the bisect, make and test processes and the
-script.
-+
-"make test" should "exit 0", if the test suite passes, and
-"exit 1" otherwise.
* Automatically bisect a broken test case:
+
$ cat ~/test.sh
#!/bin/sh
make || exit 125 # this skips broken builds
-~/check_test_case.sh # does the test case passes ?
+~/check_test_case.sh # does the test case pass?
$ git bisect start HEAD HEAD~10 -- # culprit is among the last 10
$ git bisect run ~/test.sh
------------
+
-Here "check_test_case.sh" should "exit 0" if the test case passes,
+Here we use a "test.sh" custom script. In this script, if "make"
+fails, we skip the current commit.
+"check_test_case.sh" should "exit 0" if the test case passes,
and "exit 1" otherwise.
+
-It is safer if both "test.sh" and "check_test_case.sh" scripts are
+It is safer if both "test.sh" and "check_test_case.sh" are
outside the repository to prevent interactions between the bisect,
make and test processes and the scripts.
-Author
-------
-Written by Linus Torvalds <torvalds@osdl.org>
+* Automatically bisect with temporary modifications (hot-fix):
++
+------------
+$ cat ~/test.sh
+#!/bin/sh
-Documentation
--------------
-Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.
+# tweak the working tree by merging the hot-fix branch
+# and then attempt a build
+if git merge --no-commit hot-fix &&
+ make
+then
+ # run project specific test and report its status
+ ~/check_test_case.sh
+ status=$?
+else
+ # tell the caller this is untestable
+ status=125
+fi
+
+# undo the tweak to allow clean flipping to the next commit
+git reset --hard
+
+# return control
+exit $status
+------------
++
+This applies modifications from a hot-fix branch before each test run,
+e.g. in case your build or test environment changed so that older
+revisions may need a fix which newer ones have already. (Make sure the
+hot-fix branch is based off a commit which is contained in all revisions
+which you are bisecting, so that the merge does not pull in too much, or
+use `git cherry-pick` instead of `git merge`.)
+
+* Automatically bisect a broken test case:
++
+------------
+$ git bisect start HEAD HEAD~10 -- # culprit is among the last 10
+$ git bisect run sh -c "make || exit 125; ~/check_test_case.sh"
+------------
++
+This shows that you can do without a run script if you write the test
+on a single line.
+
+SEE ALSO
+--------
+link:git-bisect-lk2009.html[Fighting regressions with git bisect],
+linkgit:git-blame[1].
GIT
---