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] [-b] [-l] [--root] [-t] [-f] [-n] [-s] [-p] [-w] [--incremental] [-L n,m] 12 [-S <revs-file>] [-M] [-C] [-C] [--since=<date>] 13 [<rev> | --contents <file>] [--] <file> 14 15DESCRIPTION 16----------- 17 18Annotates each line in the given file with information from the revision which 19last modified the line. Optionally, start annotating from the given revision. 20 21Also it can limit the range of lines annotated. 22 23This report doesn't tell you anything about lines which have been deleted or 24replaced; you need to use a tool such as gitlink:git-diff[1] or the "pickaxe" 25interface briefly mentioned in the following paragraph. 26 27Apart from supporting file annotation, git also supports searching the 28development history for when a code snippet occurred in a change. This makes it 29possible to track when a code snippet was added to a file, moved or copied 30between files, and eventually deleted or replaced. It works by searching for 31a text string in the diff. A small example: 32 33----------------------------------------------------------------------------- 34$ git log --pretty=oneline -S'blame_usage' 355040f17eba15504bad66b14a645bddd9b015ebb7 blame -S <ancestry-file> 36ea4c7f9bf69e781dd0cd88d2bccb2bf5cc15c9a7 git-blame: Make the output 37----------------------------------------------------------------------------- 38 39OPTIONS 40------- 41include::blame-options.txt[] 42 43-c:: 44 Use the same output mode as gitlink:git-annotate[1] (Default: off). 45 46--score-debug:: 47 Include debugging information related to the movement of 48 lines between files (see `-C`) and lines moved within a 49 file (see `-M`). The first number listed is the score. 50 This is the number of alphanumeric characters detected 51 to be moved between or within files. This must be above 52 a certain threshold for git-blame to consider those lines 53 of code to have been moved. 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-s:: 64 Suppress author name and timestamp from the output. 65 66-w:: 67 Ignore whitespace when comparing parent's version and 68 child's to find where the lines came from. 69 70 71THE PORCELAIN FORMAT 72-------------------- 73 74In this format, each line is output after a header; the 75header at the minimum has the first line which has: 76 77- 40-byte SHA-1 of the commit the line is attributed to; 78- the line number of the line in the original file; 79- the line number of the line in the final file; 80- on a line that starts a group of line from a different 81 commit than the previous one, the number of lines in this 82 group. On subsequent lines this field is absent. 83 84This header line is followed by the following information 85at least once for each commit: 86 87- author name ("author"), email ("author-mail"), time 88 ("author-time"), and timezone ("author-tz"); similarly 89 for committer. 90- filename in the commit the line is attributed to. 91- the first line of the commit log message ("summary"). 92 93The contents of the actual line is output after the above 94header, prefixed by a TAB. This is to allow adding more 95header elements later. 96 97 98SPECIFYING RANGES 99----------------- 100 101Unlike `git-blame` and `git-annotate` in older git, the extent 102of annotation can be limited to both line ranges and revision 103ranges. When you are interested in finding the origin for 104ll. 40-60 for file `foo`, you can use `-L` option like these 105(they mean the same thing -- both ask for 21 lines starting at 106line 40): 107 108 git blame -L 40,60 foo 109 git blame -L 40,+21 foo 110 111Also you can use regular expression to specify the line range. 112 113 git blame -L '/^sub hello {/,/^}$/' foo 114 115would limit the annotation to the body of `hello` subroutine. 116 117When you are not interested in changes older than the version 118v2.6.18, or changes older than 3 weeks, you can use revision 119range specifiers similar to `git-rev-list`: 120 121 git blame v2.6.18.. -- foo 122 git blame --since=3.weeks -- foo 123 124When revision range specifiers are used to limit the annotation, 125lines that have not changed since the range boundary (either the 126commit v2.6.18 or the most recent commit that is more than 3 127weeks old in the above example) are blamed for that range 128boundary commit. 129 130A particularly useful way is to see if an added file have lines 131created by copy-and-paste from existing files. Sometimes this 132indicates that the developer was being sloppy and did not 133refactor the code properly. You can first find the commit that 134introduced the file with: 135 136 git log --diff-filter=A --pretty=short -- foo 137 138and then annotate the change between the commit and its 139parents, using `commit{caret}!` notation: 140 141 git blame -C -C -f $commit^! -- foo 142 143 144INCREMENTAL OUTPUT 145------------------ 146 147When called with `--incremental` option, the command outputs the 148result as it is built. The output generally will talk about 149lines touched by more recent commits first (i.e. the lines will 150be annotated out of order) and is meant to be used by 151interactive viewers. 152 153The output format is similar to the Porcelain format, but it 154does not contain the actual lines from the file that is being 155annotated. 156 157. Each blame entry always starts with a line of: 158 159 <40-byte hex sha1> <sourceline> <resultline> <num_lines> 160+ 161Line numbers count from 1. 162 163. The first time that commit shows up in the stream, it has various 164 other information about it printed out with a one-word tag at the 165 beginning of each line about that "extended commit info" (author, 166 email, committer, dates, summary etc). 167 168. Unlike Porcelain format, the filename information is always 169 given and terminates the entry: 170 171 "filename" <whitespace-quoted-filename-goes-here> 172+ 173and thus it's really quite easy to parse for some line- and word-oriented 174parser (which should be quite natural for most scripting languages). 175+ 176[NOTE] 177For people who do parsing: to make it more robust, just ignore any 178lines in between the first and last one ("<sha1>" and "filename" lines) 179where you don't recognize the tag-words (or care about that particular 180one) at the beginning of the "extended information" lines. That way, if 181there is ever added information (like the commit encoding or extended 182commit commentary), a blame viewer won't ever care. 183 184 185SEE ALSO 186-------- 187gitlink:git-annotate[1] 188 189AUTHOR 190------ 191Written by Junio C Hamano <junkio@cox.net> 192 193GIT 194--- 195Part of the gitlink:git[7] suite