sed命令
sed基本用法：sed ：流编辑器 Stream EDitor。 操作纯ASCII 文本。 行编辑器 （另一种是全屏编辑器）
模式空间：
逐行读取到内存空间中，在内存中处理。 处理完成后，将模式空间的内容显示在屏幕上。默认并不对原文件进行任何处理，仅对模式空间中的数据进行处理。sed [options] 'AddressCommand' file ...... -n： 静默模式，不再默认显示模式 -i ： 直接修改原文件。 -e script -e script： 同时执行多个脚本。 -f script-file ： 指定要执行的脚本文件 -r ： 扩展正则表达式
Address: 1、 起始行 ，结束行 例如： 1,100 第一行到第100行 $ ：文件的最后一行， $-1,$-2存疑 2、 /RegExp/ 使用正则表达式指定模式。 例如： /^root/ 以root 开始的行 3、 /pattern1/,/pattern2/ 两个模式，从第一次匹配到模式1的行到 第一次匹配到模式2的行。 4、 某个行号 linenumber。 指定的行 5、起始行， +n 从指定行开始，向后的n行，包括指定行。
Command：
d：删除符合条件的行
[root@localhost ~]# sed "1,2d" /etc/fstab
# /etc/fstab
# Created by anaconda on Sat Apr 16 18:39:54 2016
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/centos-root / xfs defaults 0 0
UUID=0c8c0c2c-d3b8-4658-b899-0fed6a2e94d2 /boot xfs defaults 0 0
/dev/mapper/centos-swap swap swap defaults 0 0
[root@localhost ~]# sed "1,10d" /etc/fstab
/dev/mapper/centos-swap swap swap defaults 0 0
[root@localhost ~]# sed "/swap/d" /etc/fstab
p：显示符合条件的行
[root@localhost ~]# sed "/^\//p" /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sat Apr 16 18:39:54 2016
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/centos-root / xfs defaults 0 0
/dev/mapper/centos-root / xfs defaults 0 0
UUID=0c8c0c2c-d3b8-4658-b899-0fed6a2e94d2 /boot xfs defaults 0 0
/dev/mapper/centos-swap swap swap defaults 0 0
/dev/mapper/centos-swap swap swap defaults 0 0
[root@localhost ~]# sed -n "/^\//p" /etc/fstab
/dev/mapper/centos-root / xfs defaults 0 0
/dev/mapper/centos-swap swap swap defaults 0 0
a：在匹配到的行后面新增一行。 a \string
[root@localhost ~]# sed "/^\//a \# hello world" /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sat Apr 16 18:39:54 2016
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/centos-root / xfs defaults 0 0
# hello world
UUID=0c8c0c2c-d3b8-4658-b899-0fed6a2e94d2 /boot xfs defaults 0 0
/dev/mapper/centos-swap swap swap defaults 0 0
# hello world
[root@localhost ~]# sed "/^\//a \# hello world\n#hello linux" /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sat Apr 16 18:39:54 2016
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/centos-root / xfs defaults 0 0
# hello world
#hello linux
UUID=0c8c0c2c-d3b8-4658-b899-0fed6a2e94d2 /boot xfs defaults 0 0
/dev/mapper/centos-swap swap swap defaults 0 0
# hello world
#hello linux
i ：在匹配到的行前面新增一行。 i \string
[root@localhost ~]# sed "/^\//i \# hello world\n#hello linux" /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sat Apr 16 18:39:54 2016
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
# hello world
#hello linux
/dev/mapper/centos-root / xfs defaults 0 0
UUID=0c8c0c2c-d3b8-4658-b899-0fed6a2e94d2 /boot xfs defaults 0 0
# hello world
#hello linux
/dev/mapper/centos-swap swap swap defaults 0 0
r FILE ： 将指定文件的内容添加至指定行后，可用于合并文件。
[root@localhost ~]# sed "3r /etc/issue" /etc/fstab
#
# /etc/fstab
\S
Kernel \r on an \m
# Created by anaconda on Sat Apr 16 18:39:54 2016
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/centos-root / xfs defaults 0 0
UUID=0c8c0c2c-d3b8-4658-b899-0fed6a2e94d2 /boot xfs defaults 0 0
/dev/mapper/centos-swap swap swap defaults 0 0
[root@localhost ~]# cat /etc/issue
\S
Kernel \r on an \m
w FILE： 将指定范围的行内容另存至指定的文件夹。
[root@localhost ~]# sed "/swap/w /tmp/swap.txt" /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sat Apr 16 18:39:54 2016
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/centos-root / xfs defaults 0 0
UUID=0c8c0c2c-d3b8-4658-b899-0fed6a2e94d2 /boot xfs defaults 0 0
/dev/mapper/centos-swap swap swap defaults 0 0
[root@localhost ~]# cat /tmp/swap.txt
/dev/mapper/centos-swap swap swap defaults 0 0
s ： 查找并替换。 s/pattern/string/ 将每一行第一次被匹配到pattern的字符串替换成string。 s###，s@@@ 分隔符保持一致即可。
加修饰符
g：全局替换 s/pattern/string/g
i ：查找时，忽略大小写
[root@localhost ~]# sed "s/oot/OOT/" /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sat Apr 16 18:39:54 2016
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/centos-rOOT / xfs defaults 0 0
UUID=0c8c0c2c-d3b8-4658-b899-0fed6a2e94d2 /bOOT xfs defaults 0 0
/dev/mapper/centos-swap swap swap defaults 0 0
[root@localhost ~]# sed "s/swap/SWAP/" /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sat Apr 16 18:39:54 2016
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/centos-root / xfs defaults 0 0
UUID=0c8c0c2c-d3b8-4658-b899-0fed6a2e94d2 /boot xfs defaults 0 0
<span style="color:#ff0000;">/dev/mapper/centos-SWAP swap swap defaults 0 0</span>
[root@localhost ~]# <span style="color:#ff0000;">sed "s/swap/SWAP/g" /etc/fstab</span>
#
# /etc/fstab
# Created by anaconda on Sat Apr 16 18:39:54 2016
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/centos-root / xfs defaults 0 0
UUID=0c8c0c2c-d3b8-4658-b899-0fed6a2e94d2 /boot xfs defaults 0 0
<span style="color:#ff0000;">/dev/mapper/centos-SWAP SWAP SWAP defaults 0 0</span>
[root@localhost ~]#<span style="color:#ff0000;"> sed "s@/@#@g" /etc/fstab </span>
#
# #etc#fstab
# Created by anaconda on Sat Apr 16 18:39:54 2016
#
# Accessible filesystems, by reference, are maintained under '#dev#disk'
# See man pages fstab(5), findfs(8), mount(8) and#or blkid(8) for more info
#
#dev#mapper#centos-root # xfs defaults 0 0
UUID=0c8c0c2c-d3b8-4658-b899-0fed6a2e94d2 #boot xfs defaults 0 0
#dev#mapper#centos-swap swap swap defaults 0 0
&：引用模式匹配到的整个内容。
[root@localhost ~]# sed "s@l..e@l..er@g" /root/sed.txt
my l..er,
I l..er you.
[root@localhost ~]# sed "s@l..e@&r@g" /root/sed.txt my lover,I liker you.
[root@localhost ~]# sed "s@\(l..e\)@\1r@g" /root/sed.txt \\后向引用my lover,I liker you.
[root@localhost ~]# sed "s@l\(..e\)@L\1@g" /root/sed.txt \\将l --> L
my Love,
I Like you.
练习：
1、删除/etc/grub2.cfg 文件的行首的空白符2、替换/etc/inittab 中multi-user.target: analogous to runlevel 3 的3 为 5 3、删除/etc/inittab 中的开头的#号
[root@localhost etc]# sed "s@^#@@g" /etc/inittab3、删除/etc/inittab 中的开头的#号以及空白字符，#后有空白字符。
[root@localhost tmp]# sed "s@^#[[:space:]]\{1,\}@@g" /etc/inittab
删除某文件中空白字符后面跟#的的行中的空白字符以及#
[root@localhost tmp]# cat /tmp/sed.txt4、删除/etc/inittab中的空白行
#asdf
# hello world
# lady gaga
[root@localhost tmp]# sed "s@[[:space:]]\{1,\}#@@g" /tmp/sed.txt
#asdf
# hello world
lady gaga
[root@localhost tmp]# sed "/^$/d" /tmp/blandline.txt
5、取出一个文件路径的父目录名称。
[root@localhost tmp]# echo "/etc/rc.d" | sed -r "s@^(/.*/)[^/]+/?@\1@g"
/etc/
[root@localhost tmp]# echo "/etc/lsm/lsmd.conf" | sed -r "s@^/.*/([^/]+/?)@\1@g" \\取出文件名
lsmd.conf