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 45 1). The range can be specified with a regexp. For 46 example, `-L '/^sub esc_html /,/^}$/'` limits the 47 annotation only to the body of `esc_html` subroutine. 48 49-l, --long:: 50 Show long rev (Default: off). 51 52-t, --time:: 53 Show raw timestamp (Default: off). 54 55-S, --rev-file <revs-file>:: 56 Use revs from revs-file instead of calling gitlink:git-rev-list[1]. 57 58-f, --show-name:: 59 Show filename in the original commit. By default 60 filename is shown if there is any line that came from a 61 file with different name, due to rename detection. 62 63-n, --show-number:: 64 Show line number in the original commit (Default: off). 65 66-p, --porcelain:: 67 Show in a format designed for machine consumption. 68 69-M:: 70 Detect moving lines in the file as well. When a commit 71 moves a block of lines in a file (e.g. the original file 72 has A and then B, and the commit changes it to B and 73 then A), traditional 'blame' algorithm typically blames 74 the lines that were moved up (i.e. B) to the parent and 75 assigns blame to the lines that were moved down (i.e. A) 76 to the child commit. With this option, both groups of 77 lines are blamed on the parent. 78 79-C:: 80 In addition to `-M`, detect lines copied from other 81 files that were modified in the same commit. This is 82 useful when you reorganize your program and move code 83 around across files. When this option is given twice, 84 the command looks for copies from all other files in the 85 parent for the commit that creates the file in addition. 86 87-h, --help:: 88 Show help message. 89 90 91THE PORCELAIN FORMAT 92-------------------- 93 94In this format, each line is output after a header; the 95header at the minumum has the first line which has: 96 97- 40-byte SHA-1 of the commit the line is attributed to; 98- the line number of the line in the original file; 99- the line number of the line in the final file; 100- on a line that starts a group of line from a different 101 commit than the previous one, the number of lines in this 102 group. On subsequent lines this field is absent. 103 104This header line is followed by the following information 105at least once for each commit: 106 107- author name ("author"), email ("author-mail"), time 108 ("author-time"), and timezone ("author-tz"); similarly 109 for committer. 110- filename in the commit the line is attributed to. 111- the first line of the commit log message ("summary"). 112 113The contents of the actual line is output after the above 114header, prefixed by a TAB. This is to allow adding more 115header elements later. 116 117 118SPECIFIYING RANGES 119------------------ 120 121Unlike `git-blame` and `git-annotate` in older git, the extent 122of annotation can be limited to both line ranges and revision 123ranges. When you are interested in finding the origin for 124ll. 40-60 for file `foo`, you can use `-L` option like this: 125 126 git blame -L 40,60 foo 127 128When you are not interested in changes older than the version 129v2.6.18, or changes older than 3 weeks, you can use revision 130range specifiers similar to `git-rev-list`: 131 132 git blame v2.6.18.. -- foo 133 git blame --since=3.weeks -- foo 134 135When revision range specifiers are used to limit the annotation, 136lines that have not changed since the range boundary (either the 137commit v2.6.18 or the most recent commit that is more than 3 138weeks old in the above example) are blamed for that range 139boundary commit. 140 141A particularly useful way is to see if an added file have lines 142created by copy-and-paste from existing files. Sometimes this 143indicates that the developer was being sloppy and did not 144refactor the code properly. You can first find the commit that 145introduced the file with: 146 147 git log --diff-filter=A --pretty=short -- foo 148 149and then annotate the change between the commit and its 150parents, using `commit{caret}!` notation: 151 152 git blame -C -C -f $commit^! -- foo 153 154 155SEE ALSO 156-------- 157gitlink:git-annotate[1] 158 159AUTHOR 160------ 161Written by Junio C Hamano <junkio@cox.net> 162 163GIT 164--- 165Part of the gitlink:git[7] suite