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> | --reverse <rev>] [--] <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 21The command can also limit the range of lines annotated. 22 23The report does not tell you anything about lines which have been deleted or 24replaced; you need to use a tool such as 'git-diff' 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 linkgit: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 as having been 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:: 56--show-name:: 57 Show the filename in the original commit. By default 58 the filename is shown if there is any line that came from a 59 file with a different name, due to rename detection. 60 61-n:: 62--show-number:: 63 Show the line number in the original commit (Default: off). 64 65-s:: 66 Suppress the author name and timestamp from the output. 67 68-w:: 69 Ignore whitespace when comparing the parent's version and 70 the child's to find where the lines came from. 71 72 73THE PORCELAIN FORMAT 74-------------------- 75 76In this format, each line is output after a header; the 77header at the minimum has the first line which has: 78 79- 40-byte SHA-1 of the commit the line is attributed to; 80- the line number of the line in the original file; 81- the line number of the line in the final file; 82- on a line that starts a group of lines from a different 83 commit than the previous one, the number of lines in this 84 group. On subsequent lines this field is absent. 85 86This header line is followed by the following information 87at least once for each commit: 88 89- the author name ("author"), email ("author-mail"), time 90 ("author-time"), and timezone ("author-tz"); similarly 91 for committer. 92- the filename in the commit that the line is attributed to. 93- the first line of the commit log message ("summary"). 94 95The contents of the actual line is output after the above 96header, prefixed by a TAB. This is to allow adding more 97header elements later. 98 99 100SPECIFYING RANGES 101----------------- 102 103Unlike 'git-blame' and 'git-annotate' in older versions of git, the extent 104of the annotation can be limited to both line ranges and revision 105ranges. When you are interested in finding the origin for 106lines 40-60 for file `foo`, you can use the `-L` option like so 107(they mean the same thing -- both ask for 21 lines starting at 108line 40): 109 110 git blame -L 40,60 foo 111 git blame -L 40,+21 foo 112 113Also you can use a regular expression to specify the line range: 114 115 git blame -L '/^sub hello {/,/^}$/' foo 116 117which limits the annotation to the body of the `hello` subroutine. 118 119When you are not interested in changes older than version 120v2.6.18, or changes older than 3 weeks, you can use revision 121range specifiers similar to 'git-rev-list': 122 123 git blame v2.6.18.. -- foo 124 git blame --since=3.weeks -- foo 125 126When revision range specifiers are used to limit the annotation, 127lines that have not changed since the range boundary (either the 128commit v2.6.18 or the most recent commit that is more than 3 129weeks old in the above example) are blamed for that range 130boundary commit. 131 132A particularly useful way is to see if an added file has lines 133created by copy-and-paste from existing files. Sometimes this 134indicates that the developer was being sloppy and did not 135refactor the code properly. You can first find the commit that 136introduced the file with: 137 138 git log --diff-filter=A --pretty=short -- foo 139 140and then annotate the change between the commit and its 141parents, using `commit{caret}!` notation: 142 143 git blame -C -C -f $commit^! -- foo 144 145 146INCREMENTAL OUTPUT 147------------------ 148 149When called with `--incremental` option, the command outputs the 150result as it is built. The output generally will talk about 151lines touched by more recent commits first (i.e. the lines will 152be annotated out of order) and is meant to be used by 153interactive viewers. 154 155The output format is similar to the Porcelain format, but it 156does not contain the actual lines from the file that is being 157annotated. 158 159. Each blame entry always starts with a line of: 160 161 <40-byte hex sha1> <sourceline> <resultline> <num_lines> 162+ 163Line numbers count from 1. 164 165. The first time that a commit shows up in the stream, it has various 166 other information about it printed out with a one-word tag at the 167 beginning of each line describing the extra commit information (author, 168 email, committer, dates, summary, etc.). 169 170. Unlike the Porcelain format, the filename information is always 171 given and terminates the entry: 172 173 "filename" <whitespace-quoted-filename-goes-here> 174+ 175and thus it is really quite easy to parse for some line- and word-oriented 176parser (which should be quite natural for most scripting languages). 177+ 178[NOTE] 179For people who do parsing: to make it more robust, just ignore any 180lines between the first and last one ("<sha1>" and "filename" lines) 181where you do not recognize the tag words (or care about that particular 182one) at the beginning of the "extended information" lines. That way, if 183there is ever added information (like the commit encoding or extended 184commit commentary), a blame viewer will not care. 185 186 187MAPPING AUTHORS 188--------------- 189 190include::mailmap.txt[] 191 192 193SEE ALSO 194-------- 195linkgit:git-annotate[1] 196 197AUTHOR 198------ 199Written by Junio C Hamano <gitster@pobox.com> 200 201GIT 202--- 203Part of the linkgit:git[1] suite