1git-blame(1) 2============ 3 4NAME 5---- 6git-blame - Show what revision and author last modified each line of a file 7 8SYNOPSIS 9-------- 10[verse] 11'git-blame' [-c] [-l] [-t] [-f] [-n] [-p] [-L n,m] [-S <revs-file>] 12 [-M] [-C] [-C] [--since=<date>] [<rev>] [--] <file> 13 14DESCRIPTION 15----------- 16 17Annotates each line in the given file with information from the revision which 18last modified the line. Optionally, start annotating from the given revision. 19 20Also it can limit the range of lines annotated. 21 22This report doesn't tell you anything about lines which have been deleted or 23replaced; you need to use a tool such as gitlink:git-diff[1] or the "pickaxe" 24interface briefly mentioned in the following paragraph. 25 26Apart from supporting file annotation, git also supports searching the 27development history for when a code snippet occured in a change. This makes it 28possible to track when a code snippet was added to a file, moved or copied 29between files, and eventually deleted or replaced. It works by searching for 30a text string in the diff. A small example: 31 32----------------------------------------------------------------------------- 33$ git log --pretty=oneline -S'blame_usage' 345040f17eba15504bad66b14a645bddd9b015ebb7 blame -S <ancestry-file> 35ea4c7f9bf69e781dd0cd88d2bccb2bf5cc15c9a7 git-blame: Make the output 36----------------------------------------------------------------------------- 37 38OPTIONS 39------- 40-c, --compatibility:: 41 Use the same output mode as gitlink:git-annotate[1] (Default: off). 42 43-L n,m:: 44 Annotate only the specified line range (lines count from 1). 45 46-l, --long:: 47 Show long rev (Default: off). 48 49-t, --time:: 50 Show raw timestamp (Default: off). 51 52-S, --rev-file <revs-file>:: 53 Use revs from revs-file instead of calling gitlink:git-rev-list[1]. 54 55-f, --show-name:: 56 Show filename in the original commit. By default 57 filename is shown if there is any line that came from a 58 file with different name, due to rename detection. 59 60-n, --show-number:: 61 Show line number in the original commit (Default: off). 62 63-p, --porcelain:: 64 Show in a format designed for machine consumption. 65 66-M:: 67 Detect moving lines in the file as well. When a commit 68 moves a block of lines in a file (e.g. the original file 69 has A and then B, and the commit changes it to B and 70 then A), traditional 'blame' algorithm typically blames 71 the lines that were moved up (i.e. B) to the parent and 72 assigns blame to the lines that were moved down (i.e. A) 73 to the child commit. With this option, both groups of 74 lines are blamed on the parent. 75 76-C:: 77 In addition to `-M`, detect lines copied from other 78 files that were modified in the same commit. This is 79 useful when you reorganize your program and move code 80 around across files. When this option is given twice, 81 the command looks for copies from all other files in the 82 parent for the commit that creates the file in addition. 83 84-h, --help:: 85 Show help message. 86 87 88THE PORCELAIN FORMAT 89-------------------- 90 91In this format, each line is output after a header; the 92header at the minumum has the first line which has: 93 94- 40-byte SHA-1 of the commit the line is attributed to; 95- the line number of the line in the original file; 96- the line number of the line in the final file; 97- on a line that starts a group of line from a different 98 commit than the previous one, the number of lines in this 99 group. On subsequent lines this field is absent. 100 101This header line is followed by the following information 102at least once for each commit: 103 104- author name ("author"), email ("author-mail"), time 105 ("author-time"), and timezone ("author-tz"); similarly 106 for committer. 107- filename in the commit the line is attributed to. 108- the first line of the commit log message ("summary"). 109 110The contents of the actual line is output after the above 111header, prefixed by a TAB. This is to allow adding more 112header elements later. 113 114 115SPECIFIYING RANGES 116------------------ 117 118Unlike `git-blame` and `git-annotate` in older git, the extent 119of annotation can be limited to both line ranges and revision 120ranges. When you are interested in finding the origin for 121ll. 40-60 for file `foo`, you can use `-L` option like this: 122 123 git blame -L 40,60 foo 124 125Also you can use regular expression to specify the line range. 126 127 git blame -L '/^sub hello {/,/^}$/' foo 128 129would limit the annotation to the body of `hello` subroutine. 130 131When you are not interested in changes older than the version 132v2.6.18, or changes older than 3 weeks, you can use revision 133range specifiers similar to `git-rev-list`: 134 135 git blame v2.6.18.. -- foo 136 git blame --since=3.weeks -- foo 137 138When revision range specifiers are used to limit the annotation, 139lines that have not changed since the range boundary (either the 140commit v2.6.18 or the most recent commit that is more than 3 141weeks old in the above example) are blamed for that range 142boundary commit. 143 144A particularly useful way is to see if an added file have lines 145created by copy-and-paste from existing files. Sometimes this 146indicates that the developer was being sloppy and did not 147refactor the code properly. You can first find the commit that 148introduced the file with: 149 150 git log --diff-filter=A --pretty=short -- foo 151 152and then annotate the change between the commit and its 153parents, using `commit{caret}!` notation: 154 155 git blame -C -C -f $commit^! -- foo 156 157 158SEE ALSO 159-------- 160gitlink:git-annotate[1] 161 162AUTHOR 163------ 164Written by Junio C Hamano <junkio@cox.net> 165 166GIT 167--- 168Part of the gitlink:git[7] suite