grep用法详解

grep
grep一般格式为：
grep [选项]基本正则表达式[文件]
这里基本正则表达式可为字符串。
grep选项
常用的g r e p选项有：
-c   只输出匹配行的计数。
-i   不区分大小写（只适用于单字符） 。
-h   查询多文件时不显示文件名。
-l   查询多文件时只输出包含匹配字符的文件名。
-n   显示匹配行及行号。
-s   不显示不存在或无匹配文本的错误信息。
-v   显示不包含匹配文本的所有行。
3.grep允许使用国际字符模式匹配或匹配模式的类名形式。
类名及其等价的正则表达式

类     等价的正则表达式        类     等价的正则表达式
[ [ : u p p e r : ] ] [ A - Z ] [ [ : a l n u m : ] ] [ 0 - 9 a - zA-Z]
[ [ : l o w e r : ] ] [ a - z ] [ [ : s p a c e : ] ] [ 空格或t a b键]
[ [ : d i g i t : ] ] [ 0 - 9 ] [ [ : a l p h a : ] ] [ a - z A - Z ]

查询列表中的目录

/home/l/g/tomotoboy >ls -al|grep '^d'
drwx------   8 tomotoboy member      4096 Aug  7 13:45 .
drwxr-xr-x 202 root      root        4096 Oct 21  2008 ..
drwxr-xr-x   3 tomotoboy member      4096 Oct 20  2008 .sunstudio
drwxr-xr-x   2 tomotoboy member      4096 Aug  6 16:26 2
drwxr-xr-x   2 tomotoboy member      4096 Aug  7 19:16 c
drwxr-xr-x   2 tomotoboy member      4096 Jul 29 14:08 main
drwxr-xr-x   2 tomotoboy member      4096 Oct 21  2008 seawolf
drwxr-xr-x   2 tomotoboy member      4096 Aug  6 16:30 testdirec

查找包含'Oc'的行

/home/l/g/tomotoboy >ls -al|grep 'Oc'
drwxr-xr-x 202 root     root        4096 Oct 21  2008 ..
drwxr-xr-x   3 tomotoboy member      4096 Oct 20  2008 .sunstudio
-rwxr-xr-x   1 tomotoboy member       120 Oct 20  2008 greeting.sh
-rwxr-xr-x   1 tomotoboy member       116 Oct 20  2008 readme.sh
drwxr-xr-x   2 tomotoboy member      4096 Oct 21  2008 seawolf

显示满足匹配行的所有行的行数

/home/l/g/tomotoboy >ls -al|grep -n '4096'
2:drwx------   8 tomotoboy member      4096 Aug  7 13:45 .
3:drwxr-xr-x 202 root     root        4096 Oct 21  2008 ..
8:drwxr-xr-x   3 tomotoboy member      4096 Oct 20  2008 .sunstudio
9:drwxr-xr-x   2 tomotoboy member      4096 Aug  6 16:26 2
11:drwxr-xr-x   2 tomotoboy member      4096 Aug  7 19:16 c
41:drwxr-xr-x   2 tomotoboy member      4096 Jul 29 14:08 main
50:drwxr-xr-x   2 tomotoboy member      4096 Oct 21  2008 seawolf
57:drwxr-xr-x   2 tomotoboy member      4096 Aug  6 16:30 testdirec

显示不包含匹配行的行

/home/l/g/tomotoboy >ls -al|grep -v 'Aug'
total 14328
drwxr-xr-x 202 root     root        4096 Oct 21  2008 ..
-rw-------   1 tomotoboy member        35 Mar  4 22:21 .lesshst
drwxr-xr-x   3 tomotoboy member      4096 Oct 20  2008 .sunstudio
-rwxr--r--   1 tomotoboy member        68 Jul 30 16:28 change.sed
-rw-r--r--   1 tomotoboy member   7090822 Apr 10 11:00 core.log
-rwxr-xr-x   1 tomotoboy member      7058 Mar  4 23:17 factorial
-rw-r--r--   1 tomotoboy member        75 Mar  4 22:59 factorial.c
-rwxr-xr-x   1 tomotoboy member       120 Oct 20  2008 greeting.sh
-rw-r--r--   1 tomotoboy member         4 Jul 29 15:17 grepgrepstrings

'.'代表一个任意字符，查看包含'M.r'的行

/home/l/g/tomotoboy >ls -al|grep -n 'M.r'
5:-rw-------   1 tomotoboy member        35 Mar  4 22:21 .lesshst
20:-rwxr-xr-x   1 tomotoboy member      7058 Mar  4 23:17 factorial
21:-rw-r--r--   1 tomotoboy member        75 Mar  4 22:59 factorial.c
27:-rwxr-xr-x   1 tomotoboy member      9940 Mar  4 22:56 hello
28:-rw-r--r--   1 tomotoboy member        94 Mar  4 22:17 hello.cpp
42:-rw-r--r--   1 tomotoboy member       242 Mar  4 23:17 main.c

egrep
egrep代表expression或extended grep，适情况而定。egrep接受所有的正则表达式，egrep的一个显著特性是可以以一个文件作为保存的字符串，然后将之传给egrep作为参数，为此使用- f开关。