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] [--incremental] [-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 occurred 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--incremental:: 67 Show the result incrementally in a format designed for 68 machine consumption. 69 70-M:: 71 Detect moving lines in the file as well. When a commit 72 moves a block of lines in a file (e.g. the original file 73 has A and then B, and the commit changes it to B and 74 then A), traditional 'blame' algorithm typically blames 75 the lines that were moved up (i.e. B) to the parent and 76 assigns blame to the lines that were moved down (i.e. A) 77 to the child commit. With this option, both groups of 78 lines are blamed on the parent. 79 80-C:: 81 In addition to `-M`, detect lines copied from other 82 files that were modified in the same commit. This is 83 useful when you reorganize your program and move code 84 around across files. When this option is given twice, 85 the command looks for copies from all other files in the 86 parent for the commit that creates the file in addition. 87 88-h, --help:: 89 Show help message. 90 91 92THE PORCELAIN FORMAT 93-------------------- 94 95In this format, each line is output after a header; the 96header at the minimum has the first line which has: 97 98- 40-byte SHA-1 of the commit the line is attributed to; 99- the line number of the line in the original file; 100- the line number of the line in the final file; 101- on a line that starts a group of line from a different 102 commit than the previous one, the number of lines in this 103 group. On subsequent lines this field is absent. 104 105This header line is followed by the following information 106at least once for each commit: 107 108- author name ("author"), email ("author-mail"), time 109 ("author-time"), and timezone ("author-tz"); similarly 110 for committer. 111- filename in the commit the line is attributed to. 112- the first line of the commit log message ("summary"). 113 114The contents of the actual line is output after the above 115header, prefixed by a TAB. This is to allow adding more 116header elements later. 117 118 119SPECIFYING RANGES 120----------------- 121 122Unlike `git-blame` and `git-annotate` in older git, the extent 123of annotation can be limited to both line ranges and revision 124ranges. When you are interested in finding the origin for 125ll. 40-60 for file `foo`, you can use `-L` option like these 126(they mean the same thing -- both ask for 21 lines starting at 127line 40): 128 129 git blame -L 40,60 foo 130 git blame -L 40,+21 foo 131 132Also you can use regular expression to specify the line range. 133 134 git blame -L '/^sub hello {/,/^}$/' foo 135 136would limit the annotation to the body of `hello` subroutine. 137 138When you are not interested in changes older than the version 139v2.6.18, or changes older than 3 weeks, you can use revision 140range specifiers similar to `git-rev-list`: 141 142 git blame v2.6.18.. -- foo 143 git blame --since=3.weeks -- foo 144 145When revision range specifiers are used to limit the annotation, 146lines that have not changed since the range boundary (either the 147commit v2.6.18 or the most recent commit that is more than 3 148weeks old in the above example) are blamed for that range 149boundary commit. 150 151A particularly useful way is to see if an added file have lines 152created by copy-and-paste from existing files. Sometimes this 153indicates that the developer was being sloppy and did not 154refactor the code properly. You can first find the commit that 155introduced the file with: 156 157 git log --diff-filter=A --pretty=short -- foo 158 159and then annotate the change between the commit and its 160parents, using `commit{caret}!` notation: 161 162 git blame -C -C -f $commit^! -- foo 163 164 165INCREMENTAL OUTPUT 166------------------ 167 168When called with `--incremental` option, the command outputs the 169result as it is built. The output generally will talk about 170lines touched by more recent commits first (i.e. the lines will 171be annotated out of order) and is meant to be used by 172interactive viewers. 173 174The output format is similar to the Porcelain format, but it 175does not contain the actual lines from the file that is being 176annotated. 177 178. Each blame entry always starts with a line of: 179 180 <40-byte hex sha1> <sourceline> <resultline> <num_lines> 181+ 182Line numbers count from 1. 183 184. The first time that commit shows up in the stream, it has various 185 other information about it printed out with a one-word tag at the 186 beginning of each line about that "extended commit info" (author, 187 email, committer, dates, summary etc). 188 189. Unlike Porcelain format, the filename information is always 190 given and terminates the entry: 191 192 "filename" <whitespace-quoted-filename-goes-here> 193+ 194and thus it's really quite easy to parse for some line- and word-oriented 195parser (which should be quite natural for most scripting languages). 196+ 197[NOTE] 198For people who do parsing: to make it more robust, just ignore any 199lines in between the first and last one ("<sha1>" and "filename" lines) 200where you don't recognize the tag-words (or care about that particular 201one) at the beginning of the "extended information" lines. That way, if 202there is ever added information (like the commit encoding or extended 203commit commentary), a blame viewer won't ever care. 204 205 206SEE ALSO 207-------- 208gitlink:git-annotate[1] 209 210AUTHOR 211------ 212Written by Junio C Hamano <junkio@cox.net> 213 214GIT 215--- 216Part of the gitlink:git[7] suite