Finding Issues - Git Blame

The git blame command is really helpful for figuring out who changed which sections of a file. If you simple run 'git blame [filename]' you'll get an output of the entire file with the last commit sha, date and author for every line in the file.

$ git blame sha1_file.c
...
0fcfd160 (Linus Torvalds  2005-04-18 13:04:43 -0700    8)  */
0fcfd160 (Linus Torvalds  2005-04-18 13:04:43 -0700    9) #include "cache.h"
1f688557 (Junio C Hamano  2005-06-27 03:35:33 -0700   10) #include "delta.h"
a733cb60 (Linus Torvalds  2005-06-28 14:21:02 -0700   11) #include "pack.h"
8e440259 (Peter Eriksen   2006-04-02 14:44:09 +0200   12) #include "blob.h"
8e440259 (Peter Eriksen   2006-04-02 14:44:09 +0200   13) #include "commit.h"
8e440259 (Peter Eriksen   2006-04-02 14:44:09 +0200   14) #include "tag.h"
8e440259 (Peter Eriksen   2006-04-02 14:44:09 +0200   15) #include "tree.h"
f35a6d3b (Linus Torvalds  2007-04-09 21:20:29 -0700   16) #include "refs.h"
70f5d5d3 (Nicolas Pitre   2008-02-28 00:25:19 -0500   17) #include "pack-revindex.h"628522ec (Junio C Hamano              2007-12-29 02:05:47 -0800   18) #include "sha1-lookup.h"
...

This is often helpful if a file had a line reverted or a mistake that broke the build to help you see who changed that line last.

You can also specify a start and end line for the blame:

$>git blame -L 160,+10 sha1_file.c 
ace1534d (Junio C Hamano 2005-05-07 00:38:04 -0700       160)}
ace1534d (Junio C Hamano 2005-05-07 00:38:04 -0700       161)
0fcfd160 (Linus Torvalds 2005-04-18 13:04:43 -0700       162)/*
0fcfd160 (Linus Torvalds 2005-04-18 13:04:43 -0700       163) * NOTE! This returns a statically allocate
790296fd (Jim Meyering   2008-01-03 15:18:07 +0100       164) * careful about using it. Do an "xstrdup()
0fcfd160 (Linus Torvalds 2005-04-18 13:04:43 -0700       165) * filename.
ace1534d (Junio C Hamano 2005-05-07 00:38:04 -0700       166) *
ace1534d (Junio C Hamano 2005-05-07 00:38:04 -0700       167) * Also note that this returns the location
ace1534d (Junio C Hamano 2005-05-07 00:38:04 -0700       168) * SHA1 file can happen from any alternate 
d19938ab (Junio C Hamano 2005-05-09 17:57:56 -0700       169) * DB_ENVIRONMENT environment variable if i