{ "mode": "man", "parameter": "git-bisect", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/git-bisect/1/json", "generated": "2026-10-21T07:04:38Z", "synopsis": "git bisect ", "sections": { "NAME": { "content": "git-bisect - Use binary search to find the commit that introduced a bug\n", "subsections": [] }, "SYNOPSIS": { "content": "git bisect \n\n", "subsections": [] }, "DESCRIPTION": { "content": "The command takes various subcommands, and different options depending on the subcommand:\n\ngit bisect start [--term-(new|bad)= --term-(old|good)=]\n[--no-checkout] [--first-parent] [ [...]] [--] [...]\ngit bisect (bad|new|) []\ngit bisect (good|old|) [...]\ngit bisect terms [--term-good | --term-bad]\ngit bisect skip [(|)...]\ngit bisect reset []\ngit bisect (visualize|view)\ngit bisect replay \ngit bisect log\ngit bisect run [...]\ngit bisect help\n\nThis command uses a binary search algorithm to find which commit in your project’s history\nintroduced a bug. You use it by first telling it a \"bad\" commit that is known to contain the\nbug, and a \"good\" commit that is known to be before the bug was introduced. Then git bisect\npicks a commit between those two endpoints and asks you whether the selected commit is \"good\"\nor \"bad\". It continues narrowing down the range until it finds the exact commit that\nintroduced the change.\n\nIn fact, git bisect can be used to find the commit that changed any property of your project;\ne.g., the commit that fixed a bug, or the commit that caused a benchmark’s performance to\nimprove. To support this more general usage, the terms \"old\" and \"new\" can be used in place\nof \"good\" and \"bad\", or you can choose your own terms. See section \"Alternate terms\" below\nfor more information.\n", "subsections": [ { "name": "Basic bisect commands: start, bad, good", "content": "As an example, suppose you are trying to find the commit that broke a feature that was known\nto work in version v2.6.13-rc2 of your project. You start a bisect session as follows:\n\n$ git bisect start\n$ git bisect bad # Current version is bad\n$ git bisect good v2.6.13-rc2 # v2.6.13-rc2 is known to be good\n\n\nOnce you have specified at least one bad and one good commit, git bisect selects a commit in\nthe middle of that range of history, checks it out, and outputs something similar to the\nfollowing:\n\nBisecting: 675 revisions left to test after this (roughly 10 steps)\n\n\nYou should now compile the checked-out version and test it. If that version works correctly,\ntype\n\n$ git bisect good\n\n\nIf that version is broken, type\n\n$ git bisect bad\n\n\nThen git bisect will respond with something like\n\nBisecting: 337 revisions left to test after this (roughly 9 steps)\n\n\nKeep repeating the process: compile the tree, test it, and depending on whether it is good or\nbad run git bisect good or git bisect bad to ask for the next commit that needs testing.\n\nEventually there will be no more revisions left to inspect, and the command will print out a\ndescription of the first bad commit. The reference refs/bisect/bad will be left pointing at\nthat commit.\n" }, { "name": "Bisect reset", "content": "After a bisect session, to clean up the bisection state and return to the original HEAD,\nissue the following command:\n\n$ git bisect reset\n\n\nBy default, this will return your tree to the commit that was checked out before git bisect\nstart. (A new git bisect start will also do that, as it cleans up the old bisection state.)\n\nWith an optional argument, you can return to a different commit instead:\n\n$ git bisect reset \n\n\nFor example, git bisect reset bisect/bad will check out the first bad revision, while git\nbisect reset HEAD will leave you on the current bisection commit and avoid switching commits\nat all.\n" }, { "name": "Alternate terms", "content": "Sometimes you are not looking for the commit that introduced a breakage, but rather for a\ncommit that caused a change between some other \"old\" state and \"new\" state. For example, you\nmight be looking for the commit that introduced a particular fix. Or you might be looking for\nthe first commit in which the source-code filenames were finally all converted to your\ncompany’s naming standard. Or whatever.\n\nIn such cases it can be very confusing to use the terms \"good\" and \"bad\" to refer to \"the\nstate before the change\" and \"the state after the change\". So instead, you can use the terms\n\"old\" and \"new\", respectively, in place of \"good\" and \"bad\". (But note that you cannot mix\n\"good\" and \"bad\" with \"old\" and \"new\" in a single session.)\n\nIn this more general usage, you provide git bisect with a \"new\" commit that has some property\nand an \"old\" commit that doesn’t have that property. Each time git bisect checks out a\ncommit, you test if that commit has the property. If it does, mark the commit as \"new\";\notherwise, mark it as \"old\". When the bisection is done, git bisect will report which commit\nintroduced the property.\n\nTo use \"old\" and \"new\" instead of \"good\" and bad, you must run git bisect start without\ncommits as argument and then run the following commands to add the commits:\n\ngit bisect old []\n\n\nto indicate that a commit was before the sought change, or\n\ngit bisect new [...]\n\n\nto indicate that it was after.\n\nTo get a reminder of the currently used terms, use\n\ngit bisect terms\n\n\nYou can get just the old (respectively new) term with git bisect terms --term-old or git\nbisect terms --term-good.\n\nIf you would like to use your own terms instead of \"bad\"/\"good\" or \"new\"/\"old\", you can\nchoose any names you like (except existing bisect subcommands like reset, start, ...) by\nstarting the bisection using\n\ngit bisect start --term-old --term-new \n\n\nFor example, if you are looking for a commit that introduced a performance regression, you\nmight use\n\ngit bisect start --term-old fast --term-new slow\n\n\nOr if you are looking for the commit that fixed a bug, you might use\n\ngit bisect start --term-new fixed --term-old broken\n\n\nThen, use git bisect and git bisect instead of git bisect good and git\nbisect bad to mark commits.\n" }, { "name": "Bisect visualize/view", "content": "To see the currently remaining suspects in gitk, issue the following command during the\nbisection process (the subcommand view can be used as an alternative to visualize):\n\n$ git bisect visualize\n\n\nGit detects a graphical environment through various environment variables: DISPLAY, which is\nset in X Window System environments on Unix systems. SESSIONNAME, which is set under Cygwin\nin interactive desktop sessions. MSYSTEM, which is set under Msys2 and Git for Windows.\nSECURITYSESSIONID, which may be set on macOS in interactive desktop sessions.\n\nIf none of these environment variables is set, git log is used instead. You can also give\ncommand-line options such as -p and --stat.\n\n$ git bisect visualize --stat\n\n" }, { "name": "Bisect log and bisect replay", "content": "After having marked revisions as good or bad, issue the following command to show what has\nbeen done so far:\n\n$ git bisect log\n\n\nIf you discover that you made a mistake in specifying the status of a revision, you can save\nthe output of this command to a file, edit it to remove the incorrect entries, and then issue\nthe following commands to return to a corrected state:\n\n$ git bisect reset\n$ git bisect replay that-file\n\n" }, { "name": "Avoiding testing a commit", "content": "If, in the middle of a bisect session, you know that the suggested revision is not a good one\nto test (e.g. it fails to build and you know that the failure does not have anything to do\nwith the bug you are chasing), you can manually select a nearby commit and test that one\ninstead.\n\nFor example:\n\n$ git bisect good/bad # previous round was good or bad.\nBisecting: 337 revisions left to test after this (roughly 9 steps)\n$ git bisect visualize # oops, that is uninteresting.\n$ git reset --hard HEAD~3 # try 3 revisions before what\n# was suggested\n\n\nThen compile and test the chosen revision, and afterwards mark the revision as good or bad in\nthe usual manner.\n" }, { "name": "Bisect skip", "content": "Instead of choosing a nearby commit by yourself, you can ask Git to do it for you by issuing\nthe command:\n\n$ git bisect skip # Current version cannot be tested\n\n\nHowever, if you skip a commit adjacent to the one you are looking for, Git will be unable to\ntell exactly which of those commits was the first bad one.\n\nYou can also skip a range of commits, instead of just one commit, using range notation. For\nexample:\n\n$ git bisect skip v2.5..v2.6\n\n\nThis tells the bisect process that no commit after v2.5, up to and including v2.6, should be\ntested.\n\nNote that if you also want to skip the first commit of the range you would issue the command:\n\n$ git bisect skip v2.5 v2.5..v2.6\n\n\nThis tells the bisect process that the commits between v2.5 and v2.6 (inclusive) should be\nskipped.\n" }, { "name": "Cutting down bisection by giving more parameters to bisect start", "content": "You can further cut down the number of trials, if you know what part of the tree is involved\nin the problem you are tracking down, by specifying path parameters when issuing the bisect\nstart command:\n\n$ git bisect start -- arch/i386 include/asm-i386\n\n\nIf you know beforehand more than one good commit, you can narrow the bisect space down by\nspecifying all of the good commits immediately after the bad commit when issuing the bisect\nstart command:\n\n$ git bisect start v2.6.20-rc6 v2.6.20-rc4 v2.6.20-rc1 --\n# v2.6.20-rc6 is bad\n# v2.6.20-rc4 and v2.6.20-rc1 are good\n\n" }, { "name": "Bisect run", "content": "If you have a script that can tell if the current source code is good or bad, you can bisect\nby issuing the command:\n\n$ git bisect run myscript arguments\n\n\nNote that the script (myscript in the above example) should exit with code 0 if the current\nsource code is good/old, and exit with a code between 1 and 127 (inclusive), except 125, if\nthe current source code is bad/new.\n\nAny other exit code will abort the bisect process. It should be noted that a program that\nterminates via exit(-1) leaves $? = 255, (see the exit(3) manual page), as the value is\nchopped with & 0377.\n\nThe special exit code 125 should be used when the current source code cannot be tested. If\nthe script exits with this code, the current revision will be skipped (see git bisect skip\nabove). 125 was chosen as the highest sensible value to use for this purpose, because 126 and\n127 are used by POSIX shells to signal specific error status (127 is for command not found,\n126 is for command found but not executable—these details do not matter, as they are normal\nerrors in the script, as far as bisect run is concerned).\n\nYou may often find that during a bisect session you want to have temporary modifications\n(e.g. s/#define DEBUG 0/#define DEBUG 1/ in a header file, or \"revision that does not have\nthis commit needs this patch applied to work around another problem this bisection is not\ninterested in\") applied to the revision being tested.\n\nTo cope with such a situation, after the inner git bisect finds the next revision to test,\nthe script can apply the patch before compiling, run the real test, and afterwards decide if\nthe revision (possibly with the needed patch) passed the test and then rewind the tree to the\npristine state. Finally the script should exit with the status of the real test to let the\ngit bisect run command loop determine the eventual outcome of the bisect session.\n" } ] }, "OPTIONS": { "content": "", "subsections": [ { "name": "--no-checkout", "content": "Do not checkout the new working tree at each iteration of the bisection process. Instead\njust update a special reference named BISECTHEAD to make it point to the commit that\nshould be tested.\n\nThis option may be useful when the test you would perform in each step does not require a\nchecked out tree.\n\nIf the repository is bare, --no-checkout is assumed.\n", "long": "--no-checkout" }, { "name": "--first-parent", "content": "Follow only the first parent commit upon seeing a merge commit.\n\nIn detecting regressions introduced through the merging of a branch, the merge commit\nwill be identified as introduction of the bug and its ancestors will be ignored.\n\nThis option is particularly useful in avoiding false positives when a merged branch\ncontained broken or non-buildable commits, but the merge itself was OK.\n", "long": "--first-parent" } ] }, "EXAMPLES": { "content": "• Automatically bisect a broken build between v1.2 and HEAD:\n\n$ git bisect start HEAD v1.2 -- # HEAD is bad, v1.2 is good\n$ git bisect run make # \"make\" builds the app\n$ git bisect reset # quit the bisect session\n\n\n• Automatically bisect a test failure between origin and HEAD:\n\n$ git bisect start HEAD origin -- # HEAD is bad, origin is good\n$ git bisect run make test # \"make test\" builds and tests\n$ git bisect reset # quit the bisect session\n\n\n• Automatically bisect a broken test case:\n\n$ cat ~/test.sh\n#!/bin/sh\nmake || exit 125 # this skips broken builds\n~/checktestcase.sh # does the test case pass?\n$ git bisect start HEAD HEAD~10 -- # culprit is among the last 10\n$ git bisect run ~/test.sh\n$ git bisect reset # quit the bisect session\n\nHere we use a test.sh custom script. In this script, if make fails, we skip the current\ncommit. checktestcase.sh should exit 0 if the test case passes, and exit 1 otherwise.\n\nIt is safer if both test.sh and checktestcase.sh are outside the repository to prevent\ninteractions between the bisect, make and test processes and the scripts.\n\n• Automatically bisect with temporary modifications (hot-fix):\n\n$ cat ~/test.sh\n#!/bin/sh\n\n# tweak the working tree by merging the hot-fix branch\n# and then attempt a build\nif git merge --no-commit --no-ff hot-fix &&\nmake\nthen\n# run project specific test and report its status\n~/checktestcase.sh\nstatus=$?\nelse\n# tell the caller this is untestable\nstatus=125\nfi\n\n# undo the tweak to allow clean flipping to the next commit\ngit reset --hard\n\n# return control\nexit $status\n\nThis applies modifications from a hot-fix branch before each test run, e.g. in case your\nbuild or test environment changed so that older revisions may need a fix which newer ones\nhave already. (Make sure the hot-fix branch is based off a commit which is contained in\nall revisions which you are bisecting, so that the merge does not pull in too much, or\nuse git cherry-pick instead of git merge.)\n\n• Automatically bisect a broken test case:\n\n$ git bisect start HEAD HEAD~10 -- # culprit is among the last 10\n$ git bisect run sh -c \"make || exit 125; ~/checktestcase.sh\"\n$ git bisect reset # quit the bisect session\n\nThis shows that you can do without a run script if you write the test on a single line.\n\n• Locate a good region of the object graph in a damaged repository\n\n$ git bisect start HEAD [ ... ] --no-checkout\n$ git bisect run sh -c '\nGOOD=$(git for-each-ref \"--format=%(objectname)\" refs/bisect/good-*) &&\ngit rev-list --objects BISECTHEAD --not $GOOD >tmp.$$ &&\ngit pack-objects --stdout >/dev/null [ ... ] --no-checkout", "$ git bisect run sh -c '", "GOOD=$(git for-each-ref \"--format=%(objectname)\" refs/bisect/good-*) &&", "git rev-list --objects BISECTHEAD --not $GOOD >tmp.$$ &&", "git pack-objects --stdout >/dev/null