用[git grep](http://www.kernel.org/pub/software/scm/git/docs/git-grep.html) 命令查找Git库里面的某段文字是很方便的. 当然, 你也可以用unix下的'grep'命令进行搜索, 但是'git grep'命令能让你不用签出(checkout)历史文件, 就能查找它们. 例如, 你要看 git.git　这个仓库里每个使用'xmmap'函数的地方, 你可以运行下面的命令: ~~~ $ git grep xmmap config.c: contents = xmmap(NULL, contents_sz, PROT_READ, diff.c: s->data = xmmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0); git-compat-util.h:extern void *xmmap(void *start, size_t length, int prot, int fla read-cache.c: mmap = xmmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, refs.c: log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0); sha1_file.c: map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0); sha1_file.c: idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0); sha1_file.c: win->base = xmmap(NULL, win->len, sha1_file.c: map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, f sha1_file.c: buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0); wrapper.c:void *xmmap(void *start, size_t length, ~~~ 如果你要显示行号, 你可以添加'-n'选项: ~~~ $>git grep -n xmmap config.c:1016: contents = xmmap(NULL, contents_sz, PROT_READ, diff.c:1833: s->data = xmmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, git-compat-util.h:291:extern void *xmmap(void *start, size_t length, int prot, int read-cache.c:1178: mmap = xmmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_ refs.c:1345: log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0); sha1_file.c:377: map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0); sha1_file.c:479: idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd sha1_file.c:780: win->base = xmmap(NULL, win->len, sha1_file.c:1076: map = xmmap(NULL, *size, PROT_READ, MAP_PR sha1_file.c:2393: buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd wrapper.c:89:void *xmmap(void *start, size_t length, ~~~ 如果我们想只显示文件名, 我们可以使用'--name-onley'选项: ~~~ $>git grep --name-only xmmap config.c diff.c git-compat-util.h read-cache.c refs.c sha1_file.c wrapper.c ~~~ 我们可以用'-c'选项,可以查看每个文件里有多少行匹配内容(line matches): ~~~ $>git grep -c xmmap config.c:1 diff.c:1 git-compat-util.h:1 read-cache.c:1 refs.c:1 sha1_file.c:5 wrapper.c:1 ~~~ 现在, 如果我们要查找git仓库里某个特定版本里的内容, 我们可以像下面一样在命令行末尾加上标签名(tag reference): ~~~ $ git grep xmmap v1.5.0 v1.5.0:config.c: contents = xmmap(NULL, st.st_size, PROT_READ, v1.5.0:diff.c: s->data = xmmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, v1.5.0:git-compat-util.h:static inline void *xmmap(void *start, size_t length, v1.5.0:read-cache.c: cache_mmap = xmmap(NULL, cache_mmap_size, v1.5.0:refs.c: log_mapped = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd v1.5.0:sha1_file.c: map = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, v1.5.0:sha1_file.c: idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd v1.5.0:sha1_file.c: win->base = xmmap(NULL, win->len, v1.5.0:sha1_file.c: map = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, v1.5.0:sha1_file.c: buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd ~~~ 我可以看到"1.5.0版"和当前版本间一些区别: 在“1.5.0版"中, xmmap没有在wrapper.c中出现. 我们也可以组合一些搜索条件, 下面的命令就是查找我们在仓库的哪个地方定义了'SORT_DIRENT'. ~~~ $ git grep -e '#define' --and -e SORT_DIRENT builtin-fsck.c:#define SORT_DIRENT 0 builtin-fsck.c:#define SORT_DIRENT 1 ~~~ 我不但可以进行“与"(_both_)条件搜索操作，也可以进行"或"(_either_)条件搜索操作. ~~~ $ git grep --all-match -e '#define' -e SORT_DIRENT builtin-fsck.c:#define REACHABLE 0x0001 builtin-fsck.c:#define SEEN 0x0002 builtin-fsck.c:#define ERROR_OBJECT 01 builtin-fsck.c:#define ERROR_REACHABLE 02 builtin-fsck.c:#define SORT_DIRENT 0 builtin-fsck.c:#define DIRENT_SORT_HINT(de) 0 builtin-fsck.c:#define SORT_DIRENT 1 builtin-fsck.c:#define DIRENT_SORT_HINT(de) ((de)->d_ino) builtin-fsck.c:#define MAX_SHA1_ENTRIES (1024) builtin-fsck.c: if (SORT_DIRENT) ~~~ 我们也可以查找出符合一个条件(term)且符合两个条件(terms)之一的文件行.　例如我们要找出名字中含有‘PATH'或是'MAX'的常量定义: ~~~ $ git grep -e '#define' --and \( -e PATH -e MAX \) abspath.c:#define MAXDEPTH 5 builtin-blame.c:#define MORE_THAN_ONE_PATH (1u<<13) builtin-blame.c:#define MAXSG 16 builtin-describe.c:#define MAX_TAGS (FLAG_BITS - 1) builtin-fetch-pack.c:#define MAX_IN_VAIN 256 builtin-fsck.c:#define MAX_SHA1_ENTRIES (1024) ... ~~~ > 译者注:　就是"与"条件搜索和"或"条件搜索可以组合使用。