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] [-e] [-p] [-w] [--incremental] 12 [-L <range>] [-S <revs-file>] [-M] [-C] [-C] [-C] [--since=<date>] 13 [--ignore-rev <rev>] [--ignore-revs-file <file>] 14 [--progress] [--abbrev=<n>] [<rev> | --contents <file> | --reverse <rev>..<rev>] 15 [--] <file> 16 17DESCRIPTION 18----------- 19 20Annotates each line in the given file with information from the revision which 21last modified the line. Optionally, start annotating from the given revision. 22 23When specified one or more times, `-L` restricts annotation to the requested 24lines. 25 26The origin of lines is automatically followed across whole-file 27renames (currently there is no option to turn the rename-following 28off). To follow lines moved from one file to another, or to follow 29lines that were copied and pasted from another file, etc., see the 30`-C` and `-M` options. 31 32The report does not tell you anything about lines which have been deleted or 33replaced; you need to use a tool such as 'git diff' or the "pickaxe" 34interface briefly mentioned in the following paragraph. 35 36Apart from supporting file annotation, Git also supports searching the 37development history for when a code snippet occurred in a change. This makes it 38possible to track when a code snippet was added to a file, moved or copied 39between files, and eventually deleted or replaced. It works by searching for 40a text string in the diff. A small example of the pickaxe interface 41that searches for `blame_usage`: 42 43----------------------------------------------------------------------------- 44$ git log --pretty=oneline -S'blame_usage' 455040f17eba15504bad66b14a645bddd9b015ebb7 blame -S <ancestry-file> 46ea4c7f9bf69e781dd0cd88d2bccb2bf5cc15c9a7 git-blame: Make the output 47----------------------------------------------------------------------------- 48 49OPTIONS 50------- 51include::blame-options.txt[] 52 53-c:: 54 Use the same output mode as linkgit:git-annotate[1] (Default: off). 55 56--score-debug:: 57 Include debugging information related to the movement of 58 lines between files (see `-C`) and lines moved within a 59 file (see `-M`). The first number listed is the score. 60 This is the number of alphanumeric characters detected 61 as having been moved between or within files. This must be above 62 a certain threshold for 'git blame' to consider those lines 63 of code to have been moved. 64 65-f:: 66--show-name:: 67 Show the filename in the original commit. By default 68 the filename is shown if there is any line that came from a 69 file with a different name, due to rename detection. 70 71-n:: 72--show-number:: 73 Show the line number in the original commit (Default: off). 74 75-s:: 76 Suppress the author name and timestamp from the output. 77 78-e:: 79--show-email:: 80 Show the author email instead of author name (Default: off). 81 This can also be controlled via the `blame.showEmail` config 82 option. 83 84-w:: 85 Ignore whitespace when comparing the parent's version and 86 the child's to find where the lines came from. 87 88--abbrev=<n>:: 89 Instead of using the default 7+1 hexadecimal digits as the 90 abbreviated object name, use <n>+1 digits. Note that 1 column 91 is used for a caret to mark the boundary commit. 92 93 94THE PORCELAIN FORMAT 95-------------------- 96 97In this format, each line is output after a header; the 98header at the minimum has the first line which has: 99 100- 40-byte SHA-1 of the commit the line is attributed to; 101- the line number of the line in the original file; 102- the line number of the line in the final file; 103- on a line that starts a group of lines from a different 104 commit than the previous one, the number of lines in this 105 group. On subsequent lines this field is absent. 106 107This header line is followed by the following information 108at least once for each commit: 109 110- the author name ("author"), email ("author-mail"), time 111 ("author-time"), and time zone ("author-tz"); similarly 112 for committer. 113- the filename in the commit that the line is attributed to. 114- the first line of the commit log message ("summary"). 115 116The contents of the actual line is output after the above 117header, prefixed by a TAB. This is to allow adding more 118header elements later. 119 120The porcelain format generally suppresses commit information that has 121already been seen. For example, two lines that are blamed to the same 122commit will both be shown, but the details for that commit will be shown 123only once. This is more efficient, but may require more state be kept by 124the reader. The `--line-porcelain` option can be used to output full 125commit information for each line, allowing simpler (but less efficient) 126usage like: 127 128 # count the number of lines attributed to each author 129 git blame --line-porcelain file | 130 sed -n 's/^author //p' | 131 sort | uniq -c | sort -rn 132 133 134SPECIFYING RANGES 135----------------- 136 137Unlike 'git blame' and 'git annotate' in older versions of git, the extent 138of the annotation can be limited to both line ranges and revision 139ranges. The `-L` option, which limits annotation to a range of lines, may be 140specified multiple times. 141 142When you are interested in finding the origin for 143lines 40-60 for file `foo`, you can use the `-L` option like so 144(they mean the same thing -- both ask for 21 lines starting at 145line 40): 146 147 git blame -L 40,60 foo 148 git blame -L 40,+21 foo 149 150Also you can use a regular expression to specify the line range: 151 152 git blame -L '/^sub hello {/,/^}$/' foo 153 154which limits the annotation to the body of the `hello` subroutine. 155 156When you are not interested in changes older than version 157v2.6.18, or changes older than 3 weeks, you can use revision 158range specifiers similar to 'git rev-list': 159 160 git blame v2.6.18.. -- foo 161 git blame --since=3.weeks -- foo 162 163When revision range specifiers are used to limit the annotation, 164lines that have not changed since the range boundary (either the 165commit v2.6.18 or the most recent commit that is more than 3 166weeks old in the above example) are blamed for that range 167boundary commit. 168 169A particularly useful way is to see if an added file has lines 170created by copy-and-paste from existing files. Sometimes this 171indicates that the developer was being sloppy and did not 172refactor the code properly. You can first find the commit that 173introduced the file with: 174 175 git log --diff-filter=A --pretty=short -- foo 176 177and then annotate the change between the commit and its 178parents, using `commit^!` notation: 179 180 git blame -C -C -f $commit^! -- foo 181 182 183INCREMENTAL OUTPUT 184------------------ 185 186When called with `--incremental` option, the command outputs the 187result as it is built. The output generally will talk about 188lines touched by more recent commits first (i.e. the lines will 189be annotated out of order) and is meant to be used by 190interactive viewers. 191 192The output format is similar to the Porcelain format, but it 193does not contain the actual lines from the file that is being 194annotated. 195 196. Each blame entry always starts with a line of: 197 198 <40-byte hex sha1> <sourceline> <resultline> <num_lines> 199+ 200Line numbers count from 1. 201 202. The first time that a commit shows up in the stream, it has various 203 other information about it printed out with a one-word tag at the 204 beginning of each line describing the extra commit information (author, 205 email, committer, dates, summary, etc.). 206 207. Unlike the Porcelain format, the filename information is always 208 given and terminates the entry: 209 210 "filename" <whitespace-quoted-filename-goes-here> 211+ 212and thus it is really quite easy to parse for some line- and word-oriented 213parser (which should be quite natural for most scripting languages). 214+ 215[NOTE] 216For people who do parsing: to make it more robust, just ignore any 217lines between the first and last one ("<sha1>" and "filename" lines) 218where you do not recognize the tag words (or care about that particular 219one) at the beginning of the "extended information" lines. That way, if 220there is ever added information (like the commit encoding or extended 221commit commentary), a blame viewer will not care. 222 223 224MAPPING AUTHORS 225--------------- 226 227include::mailmap.txt[] 228 229 230SEE ALSO 231-------- 232linkgit:git-annotate[1] 233 234GIT 235--- 236Part of the linkgit:git[1] suite