NAME
----
- git-bisect - Find the change that introduced a bug by binary search
+ git-bisect - Find by binary search the change that introduced a bug
SYNOPSIS
Basic bisect commands: start, bad, good
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- The way you use it is:
+ Using the Linux kernel tree as an example, basic use of the bisect
+ command is as follows:
------------------------------------------------
$ git bisect start
# 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 have specified at least one bad and one good version, the
+ command bisects the revision tree and outputs something similar to
+ the following:
------------------------------------------------
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
+ The state in the middle of the set of revisions is then checked out.
+ You would now compile that kernel and boot it. If the booted kernel
+ works correctly, you would then issue the following command:
------------------------------------------------
$ git bisect good # this one is good
------------------------------------------------
- which will now say
+ The output of this command would be something similar to the following:
------------------------------------------------
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.
+ You keep repeating this process, compiling the tree, testing it, and
+ depending on whether it is good or bad issuing the command "git bisect good"
+ or "git bisect bad" to 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".
+ Eventually there will be no more revisions left to bisect, and you
+ will have been left with the first bad kernel revision in "refs/bisect/bad".
Bisect reset
~~~~~~~~~~~~
- Oh, and then after you want to reset to the original head, do a
+ To return to the original head after a bisect session, you issue the
+ following command:
------------------------------------------------
$ git bisect reset
------------------------------------------------
- to get back to the original branch, instead of being on the bisection
- commit ("git bisect start" will do that for you too, actually: it will
- reset the bisection state).
+ 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).
Bisect visualize
~~~~~~~~~~~~~~~~
- During the bisection process, you can say
+ To see the currently remaining suspects in 'gitk', the following command
+ is issued during the bisection process:
------------
$ git bisect visualize
------------
- to see the currently remaining suspects in 'gitk'. `visualize` is a bit
- too long to type and `view` is provided as a synonym.
+ `view` may also be used as a synonym for `visualize`.
- If 'DISPLAY' environment variable is not set, 'git log' is used
- instead. You can even give command line options such as `-p` and
+ If the 'DISPLAY' environment variable is not set, 'git log' is used
+ instead. You can also give command line options such as `-p` and
`--stat`.
------------
Bisect log and bisect replay
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- The good/bad input is logged, and
+ After having marked revisions as good or bad, you issue the following
+ command to show what has been done so far:
------------
$ 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 you discover that you made a mistake in specifying the status of a
+ revision, you can save the output of this command to a file, edit it to
+ remove the incorrect entries, and then issue the following commands to
+ return to a corrected state:
------------
+ $ git bisect reset
$ git bisect replay that-file
------------
- if you find later you made a mistake telling good/bad about a
- revision.
-
- Avoiding to test a commit
+ Avoiding testing 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
+ 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
- want to find a near-by commit and try that instead.
+ want to find a nearby commit and try that instead.
- It goes something like this:
+ For example:
------------
- $ git bisect good/bad # previous round was good/bad.
+ $ git bisect good/bad # previous round was good or 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
+ $ git reset --hard HEAD~3 # try 3 revisions before what
# 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 chosen revision. Afterwards the revision
+ is marked as good or bad in the usual manner.
Bisect skip
~~~~~~~~~~~~
- Instead of choosing by yourself a nearby commit, you may just want git
- to do it for you using:
+ Instead of choosing by yourself a nearby commit, you can ask git
+ to do it for you by issuing the command:
------------
$ 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.
+ eventually not be able 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
------------
- would mean that no commit between `v2.5` excluded and `v2.6` included
- can be tested.
+ The effect of this would be that no commit between `v2.5` excluded and
+ `v2.6` included could be tested.
- Note that if you want to also skip the first commit of a range you can
- use something like:
+ 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
------------
- and the commit pointed to by `v2.5` will be skipped too.
+ This would cause the commits between `v2.5` included and `v2.6` included
+ to be skipped.
+
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:
+ 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 specifying
+ path parameters when issuing the `bisect start` command:
------------
$ 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:
+ If you know beforehand more than one good commit, you can narrow the
+ bisect space down by specifying all of the good commits immediately after
+ the bad commit when issuing the `bisect start` command:
------------
$ git bisect start v2.6.20-rc6 v2.6.20-rc4 v2.6.20-rc1 --
~~~~~~~~~~
If you have a script that can tell if the current source code is good
- or bad, you can automatically bisect using:
+ or bad, you can bisect by issuing the command:
------------
-$ git bisect run my_script
+$ git bisect run my_script arguments
------------
- 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
+ Note that the script (`my_script` in the above example) should
+ exit with code 0 if the current source code is good, and 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".)
+ Any other exit code will abort the bisect process. It should be noted
+ that a program that terminates via "exit(-1)" leaves $? = 255, (see the
+ exit(3) manual page), as 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.
+ cannot be tested. If the 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.
+ 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
+ header file, or "revision that does not have this commit needs this
+ patch applied to work around another 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 the "git bisect run" command loop to
- determine the outcome.
+ next revision to test, the script can apply the patch
+ before compiling, run the real test, and afterwards decide if the
+ revision (possibly with the needed patch) passed the test and then
+ rewind the tree to the pristine state. Finally the script should exit
+ with the status of the real test to let the "git bisect run" command loop
+ determine the eventual outcome of the bisect session.
EXAMPLES
--------
$ git bisect run make # "make" builds the app
------------
+* Automatically bisect a test failure between origin and HEAD:
++
+------------
+$ git bisect start HEAD origin -- # HEAD is bad, origin is good
+$ git bisect run make test # "make test" builds and tests
+------------
+
* Automatically bisect a broken test suite:
+
------------
$ cat ~/test.sh
#!/bin/sh
- make || exit 125 # this "skip"s broken builds
+ 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
------------
+
Here we use a "test.sh" custom script. In this script, if "make"
- fails, we "skip" the current commit.
+ fails, we skip the current commit.
+
- It's safer to use a custom script outside the repo to prevent
+ It is safer to use a custom script outside the repository to prevent
interactions between the bisect, make and test processes and the
script.
+
- And "make test" should "exit 0", if the test suite passes, and
- "exit 1" (for example) otherwise.
+ "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 "skip"s broken builds
+ make || exit 125 # this skips broken builds
~/check_test_case.sh # does the test case passes ?
$ 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,
- and "exit 1" (for example) otherwise.
+ Here "check_test_case.sh" should "exit 0" if the test case passes,
+ and "exit 1" otherwise.
+
- It's safer if both "test.sh" and "check_test_case.sh" scripts are
- outside the repo to prevent interactions between the bisect, make and
- test processes and the scripts.
+ It is safer if both "test.sh" and "check_test_case.sh" scripts are
+ outside the repository to prevent interactions between the bisect,
+ make and test processes and the scripts.
+* Automatically bisect a broken test suite:
++
+------------
+$ git bisect start HEAD HEAD~10 -- # culprit is among the last 10
+$ git bisect run sh -c "make || exit 125; ~/check_test_case.sh"
+------------
++
+Does the same as the previous example, but on a single line.
+
Author
------
Written by Linus Torvalds <torvalds@osdl.org>
DESCRIPTION
-----------
- With no arguments, existing branches are listed, the current branch will
+ With no arguments, existing branches are listed and the current branch will
be highlighted with an asterisk. Option `-r` causes the remote-tracking
branches to be listed, and option `-a` shows both.
- With `--contains`, shows only the branches that contains the named commit
- (in other words, the branches whose tip commits are descendant of the
+ With `--contains`, shows only the branches that contain the named commit
+ (in other words, the branches whose tip commits are descendants of the
named commit). With `--merged`, only branches merged into the named
commit (i.e. the branches whose tip commits are reachable from the named
commit) will be listed. With `--no-merged` only branches not merged into
- the named commit will be listed. Missing <commit> argument defaults to
- 'HEAD' (i.e. the tip of the current branch).
+ the named commit will be listed. If the <commit> argument is missing it
+ defaults to 'HEAD' (i.e. the tip of the current branch).
- In its second form, a new branch named <branchname> will be created.
+ In the command's second form, a new branch named <branchname> will be created.
It will start out with a head equal to the one given as <start-point>.
If no <start-point> is given, the branch will be created with a head
equal to that of the currently checked out branch.
Use -r together with -d to delete remote-tracking branches. Note, that it
only makes sense to delete remote-tracking branches if they no longer exist
- in remote repository or if 'git-fetch' was configured not to fetch
- them again. See also 'prune' subcommand of linkgit:git-remote[1] for way to
- clean up all obsolete remote-tracking branches.
+ in the remote repository or if 'git-fetch' was configured not to fetch
+ them again. See also the 'prune' subcommand of linkgit:git-remote[1] for a
+ way to clean up all obsolete remote-tracking branches.
OPTIONS
based sha1 expressions such as "<branchname>@\{yesterday}".
-f::
- Force the creation of a new branch even if it means deleting
- a branch that already exists with the same name.
+ Reset <branchname> to <startpoint> if <branchname> exists
+ already. Without `-f` 'git-branch' refuses to change an existing branch.
-m::
Move/rename a branch and the corresponding reflog.
-M::
- Move/rename a branch even if the new branchname already exists.
+ Move/rename a branch even if the new branch name already exists.
--color::
Color branches to highlight current, local, and remote branches.
Show sha1 and commit subject line for each head.
--abbrev=<length>::
- Alter minimum display length for sha1 in output listing,
- default value is 7.
+ Alter the sha1's minimum display length in the output listing.
+ The default value is 7.
--no-abbrev::
- Display the full sha1s in output listing rather than abbreviating them.
+ Display the full sha1s in the output listing rather than abbreviating them.
--track::
- When creating a new branch, set up configuration so that 'git-pull'
+ When creating a new branch, set up the configuration so that 'git-pull'
will automatically retrieve data from the start point, which must be
a branch. Use this if you always pull from the same upstream branch
- into the new branch, and if you don't want to use "git pull
+ into the new branch, and if you do not want to use "git pull
<repository> <refspec>" explicitly. This behavior is the default
when the start point is a remote branch. Set the
branch.autosetupmerge configuration variable to `false` if you want
<newbranch>::
The new name for an existing branch. The same restrictions as for
- <branchname> applies.
+ <branchname> apply.
Examples
--------
- Start development off of a known tag::
+ Start development from a known tag::
+
------------
$ git clone git://git.kernel.org/pub/scm/.../linux-2.6 my2.6
<1> This step and the next one could be combined into a single step with
"checkout -b my2.6.14 v2.6.14".
- Delete unneeded branch::
+ Delete an unneeded branch::
+
------------
$ git clone git://git.kernel.org/.../git.git my.git
$ git branch -D test <2>
------------
+
- <1> Delete remote-tracking branches "todo", "html", "man". Next 'fetch' or
- 'pull' will create them again unless you configure them not to. See
- linkgit:git-fetch[1].
- <2> Delete "test" branch even if the "master" branch (or whichever branch is
- currently checked out) does not have all commits from test branch.
+ <1> Delete the remote-tracking branches "todo", "html" and "man". The next
+ 'fetch' or 'pull' will create them again unless you configure them not to.
+ See linkgit:git-fetch[1].
+ <2> Delete the "test" branch even if the "master" branch (or whichever branch
+ is currently checked out) does not have all commits from the test branch.
Notes
-----
- If you are creating a branch that you want to immediately checkout, it's
+ If you are creating a branch that you want to checkout immediately, it is
easier to use the git checkout command with its `-b` option to create
a branch and check it out with a single command.
- The options `--contains`, `--merged` and `--no-merged` serves three related
+ The options `--contains`, `--merged` and `--no-merged` serve three related
but different purposes:
- `--contains <commit>` is used to find all branches which will need