一sed介绍
三剑客是grep,sed，awk,功能都很强大。
其中sed是Stream EDitor,流编辑器 行，编辑器的简写，它一次处理一行内容。
sed的强大在于可以对文件进行修改，很适合在脚本中使用，就不需要在vim中修改文件。
处理时把当前处理的行存储在临时缓冲区中，称为“模式空间”（patternspace），
接着用sed命令处理缓冲区中的内容，处理完成后，把缓冲区的内容送往屏幕。
然后读入下行，执行下一个循环。如果没有使诸如‘D’的特殊命令，那会在两个循环之间清空模式空间，但不会清空保留空间。
这样不断重复，直到文件末尾。文件内容并没有改变，除非你使用重定向存储输出。
功能：主要用来自动编辑一个或多个文件,简化对文件的反复操作,编写转换程序等。
官方参考文档：http://www.gnu.org/software/sed/manual/sed.html
默认是基于GNU项目开发出来的软件
二sed的工作原理
sed会自动在内存开辟一块空间给自己使用，这块内存空间叫做模式空间。
一个文件里面有很多行，sed每次读取文件中的一行，读取到自己的内存空间，还可以根据sed指令对一行行进行切割。
处理完了一行，这行就没有了，接着读取下面的行内容。
上面的处理是全自动的，相当于其内置了循环。
三sed工具的使用
（一）用法
sed [option]... 'script' inputfile...
注意脚本不是shell脚本，而是sed自带的语言。
脚本的格式由两部分组合 script:'地址 命令'
地址就是文件的行，读入一行要看是否符合地址定义的行。
最简单的就是不写地址，只有命令。
（二）常用选项
-n：不输出模式空间内容到屏幕，即不自动打印
n是silent的简写
-n, --quiet, --silent
suppress automatic printing of pattern space
-e: 多点编辑
-e script, --expression=script
add the script to the commands to be executed
指定pattern 和对应的 command
-f：/ PATH/SCRIPT_FILE : 从指定文件中读取编辑脚本
-f script-file, --file=script-file
add the contents of script-file to the commands to be executed
-r: 支持使用扩展正则表达式
-r, --regexp-extended
use extended regular expressions in the script.
-i.bak: 备份文件并原处编辑
-i[SUFFIX], --in-place[=SUFFIX]
edit files in place （makes backup if SUFFIX supplied)
（三）编辑命令
查看帮助文档
d: 删除模式空间匹配的行，并立即启用下一轮循环
d Delete pattern space. Start next cycle.
p：打印当前模式空间内容，追加到默认输出之后
p Print the current pattern space.
P Print up to the first embedded newline of the current pattern space.
a [\]text：在指定行后面追加文本支持使用\n实现多行追加
a \ text Append text, which has each embedded newline preceded by a backslash.
i [\]text：在行前面插入文本
i \ text Insert text, which has each embedded newline preceded by a backslash.
c [\]text：替换行为单行或多行文本
c \
text Replace the selected lines with text, which has each embedded newline preceded by a backslash.
w /path/somefile: 保存模式匹配的行至指定文件
w filename
Write the current pattern space to filename.
r /path/somefile：读取指定文件的文本至模式空间中匹配到的行后
r filename
Append text read from filename.
=: 为模式空间中的行打印行号
= Print the current line number.
!:模式空间中匹配行取反处理
（四）脚本格式介绍
脚本是由地址和命令组合成的。
地址就是文件的行，读入一行要看是否符合地址定义的行。最简单是不写地址，只有命令。
1地址定界
（1） 不给地址：对全文进行处理，地址就相当于过滤条件。
就像你是人，指的是全地球人类的一员。
1）默认就会自动打印，所以是打印两遍。
[root@centos72 ~]# sed 'p' /etc/issue \S \S Kernel \r on an \m Kernel \r on an \m
不加引号也可以
[root@centos65 ~]# sed p /etc/issue
CentOS release 6.8 （Final)
CentOS release 6.8 （Final) Kernel \r on an \m Kernel \r on an \m
2）自动打印关闭
把自动打印关闭，现在就打印1遍。
注意-n只要不加在命令前面即可。
-n, --quiet, --silent
suppress automatic printing of pattern space
p Print the current pattern space.
P Print up to the first embedded newline of the current pattern space.
[root@centos72 ~]# sed 'p' /etc/issue -n \S Kernel \r on an \m [root@centos72 ~]# sed -n 'p' /etc/issue \S Kernel \r on an \m
上面单纯的打印没有什么实际意义，因为cat也可以实现
[root@centos72 ~]# cat /etc/issue \S Kernel \r on an \m
（2）单地址：
#: 指定的行，$：最后一行，/pattern/：被此处模式所能够匹配到的每一行
1）#=2表示文件的第2行打印
[root@centos72 ~]# sed '2p' /etc/issue \S Kernel \r on an \m Kernel \r on an \m [root@centos72 ~]# sed -n '2p' /etc/issue Kernel \r on an \m
2）地址为空并且自动打印，那么就是把文件内容全部打印一遍
[root@centos72 ~]# sed '' /etc/issue \S Kernel \r on an \m
3）使用sed读取键盘输入的内容
因为把自动打印关了，只对第2行打印了1遍
[root@centos72 ~]# sed -n '2p' aaaaa bbbbb
#输入的内容 bbbbb
#自动打印的 ccccc ddddd
4）
sed默认是支持标准输入，可以使用管道传输，适合显示命令结果的第几行。
这种方法可以取代head，tail。很多以前麻烦的事，sed都可以解决的。
方法多了就可以找到和使用更好的方法，这和学数学一样，解题方法不只一种，发散思维的前提是对知识的积累和掌握。
显示网络接口信息
[root@centos72 ~]# ifconfig
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.137.72 netmask 255.255.255.0 broadcast 192.168.137.255
inet6 fe80::b029:2522:876f:5456 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:fc:69:f8 txqueuelen 1000 （Ethernet)
RX packets 1889 bytes 178723 （174.5 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1118 bytes 173152 （169.0 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 （Local Loopback)
RX packets 0 bytes 0 （0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 （0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
打印标准输入网络接口信息的第2行内容
[root@centos72 ~]# ifconfig | sed -n '2p'
inet 192.168.137.72 netmask 255.255.255.0 broadcast 192.168.137.255
5）
$：最后一行
打印文件最后一行的信息
[root@centos72 ~]# sed '' /etc/fstab # # /etc/fstab # Created by anaconda on Sun Jan 13 00:14:21 2019 # # Accessible filesystems, by reference, are maintained under '/dev/disk' # See man pages fstab（5), findfs（8), mount（8) and/or blkid（8) for more info # UUID=5998ead0-b370-4859-9153-ecf4e2b9dd84 / xfs defaults 0 0 UUID=ac6bb7e3-fa78-4eb2-b00d-e85c421c1bb0 /app xfs defaults 0 0 UUID=92886c3f-42a3-40f4-8cf7-c6890ca3a52e /boot xfs defaults 0 0 UUID=104520e1-0e97-4248-8fd0-a21e7d88a881 swap swap defaults 0 0 /dev/cdrom /mnt iso9660 defaults 0 0 [root@centos72 ~]# sed -n '$p' /etc/fstab /dev/cdrom /mnt iso9660 defaults 0 0
6）
/pattern/：被此处模式所能够匹配到的每一行，模式支持正则表达式
打印文件以U开头的所有行
[root@centos72 ~]# sed -n '/^U/p' /etc/fstab UUID=5998ead0-b370-4859-9153-ecf4e2b9dd84 / xfs defaults 0 0 UUID=ac6bb7e3-fa78-4eb2-b00d-e85c421c1bb0 /app xfs defaults 0 0 UUID=92886c3f-42a3-40f4-8cf7-c6890ca3a52e /boot xfs defaults 0 0 UUID=104520e1-0e97-4248-8fd0-a21e7d88a881 swap swap defaults 0 0
/pattern/前后不加引号也可以
[root@centos72 ~]# sed -n /^U/p /etc/fstab UUID=5998ead0-b370-4859-9153-ecf4e2b9dd84 / xfs defaults 0 0 UUID=ac6bb7e3-fa78-4eb2-b00d-e85c421c1bb0 /app xfs defaults 0 0 UUID=92886c3f-42a3-40f4-8cf7-c6890ca3a52e /boot xfs defaults 0 0 UUID=104520e1-0e97-4248-8fd0-a21e7d88a881 swap swap defaults 0 0
注意地址后面一定要加上命令，否则会报错
[root@centos72 ~]# sed '/^U/' /etc/fstab sed: -e expression #1, char 4: missing command
grep更方便
[root@centos72 ~]# grep ^U /etc/fstab UUID=5998ead0-b370-4859-9153-ecf4e2b9dd84 / xfs defaults 0 0 UUID=ac6bb7e3-fa78-4eb2-b00d-e85c421c1bb0 /app xfs defaults 0 0 UUID=92886c3f-42a3-40f4-8cf7-c6890ca3a52e /boot xfs defaults 0 0 UUID=104520e1-0e97-4248-8fd0-a21e7d88a881 swap swap defaults 0 0 [root@centos72 ~]# grep '^U' /etc/fstab UUID=5998ead0-b370-4859-9153-ecf4e2b9dd84 / xfs defaults 0 0 UUID=ac6bb7e3-fa78-4eb2-b00d-e85c421c1bb0 /app xfs defaults 0 0 UUID=92886c3f-42a3-40f4-8cf7-c6890ca3a52e /boot xfs defaults 0 0 UUID=104520e1-0e97-4248-8fd0-a21e7d88a881 swap swap defaults 0 0
（3）地址范围，也就是第几行到第几行
#,#
#,+#
/pat1/,/pat2/
#,/pat1/
1）
#,#
nl /etc/fstab 显示此文件的所有行号
[root@centos72 ~]# nl /etc/fstab
1 #
2 # /etc/fstab
3 # Created by anaconda on Sun Jan 13 00:14:21 2019
4 #
5 # Accessible filesystems, by reference, are maintained under '/dev/disk'
6 # See man pages fstab（5), findfs（8), mount（8) and/or blkid（8) for more info
7 #
8 UUID=5998ead0-b370-4859-9153-ecf4e2b9dd84 / xfs defaults 0 0
9 UUID=ac6bb7e3-fa78-4eb2-b00d-e85c421c1bb0 /app xfs defaults 0 0
10 UUID=92886c3f-42a3-40f4-8cf7-c6890ca3a52e /boot xfs defaults 0 0
11 UUID=104520e1-0e97-4248-8fd0-a21e7d88a881 swap swap defaults 0 0
12 /dev/cdrom /mnt iso9660 defaults 0 0
[root@centos72 ~]# sed -n '8,12p' /etc/fstab
#
UUID=5998ead0-b370-4859-9153-ecf4e2b9dd84 / xfs defaults 0 0
UUID=ac6bb7e3-fa78-4eb2-b00d-e85c421c1bb0 /app xfs defaults 0 0
UUID=92886c3f-42a3-40f4-8cf7-c6890ca3a52e /boot xfs defaults 0 0
UUID=104520e1-0e97-4248-8fd0-a21e7d88a881 swap swap defaults 0 0
sed的行号是包括空行的
使用cat -n打印行号更准确。
[root@centos72 ~]# cat -n /etc/fstab
1
2 #
3 # /etc/fstab
4 # Created by anaconda on Sun Jan 13 00:14:21 2019
5 #
6 # Accessible filesystems, by reference, are maintained under '/dev/disk'
7 # See man pages fstab（5), findfs（8), mount（8) and/or blkid（8) for more info
8 #
9 UUID=5998ead0-b370-4859-9153-ecf4e2b9dd84 / xfs defaults 0 0
10 UUID=ac6bb7e3-fa78-4eb2-b00d-e85c421c1bb0 /app xfs defaults 0 0
11 UUID=92886c3f-42a3-40f4-8cf7-c6890ca3a52e /boot xfs defaults 0 0
12 UUID=104520e1-0e97-4248-8fd0-a21e7d88a881 swap swap defaults 0 0
13 /dev/cdrom /mnt iso9660 defaults 0 0
[root@centos72 ~]# sed -n '9,13p' /etc/fstab
UUID=5998ead0-b370-4859-9153-ecf4e2b9dd84 / xfs defaults 0 0 UUID=ac6bb7e3-fa78-4eb2-b00d-e85c421c1bb0 /app xfs defaults 0 0 UUID=92886c3f-42a3-40f4-8cf7-c6890ca3a52e /boot xfs defaults 0 0 UUID=104520e1-0e97-4248-8fd0-a21e7d88a881 swap swap defaults 0 0 /dev/cdrom /mnt iso9660 defaults 0 0 [root@centos72 ~]# sed -n '9,12p' /etc/fstab UUID=5998ead0-b370-4859-9153-ecf4e2b9dd84 / xfs defaults 0 0 UUID=ac6bb7e3-fa78-4eb2-b00d-e85c421c1bb0 /app xfs defaults 0 0 UUID=92886c3f-42a3-40f4-8cf7-c6890ca3a52e /boot xfs defaults 0 0 UUID=104520e1-0e97-4248-8fd0-a21e7d88a881 swap swap defaults 0 0
2）
#,+# 从第几行到本行之后的第几行
[root@centos72 ~]# cat -n /etc/fstab
1
2 #
3 # /etc/fstab
4 # Created by anaconda on Sun Jan 13 00:14:21 2019
5 #
6 # Accessible filesystems, by reference, are maintained under '/dev/disk'
7 # See man pages fstab（5), findfs（8), mount（8) and/or blkid（8) for more info
8 #
9 UUID=5998ead0-b370-4859-9153-ecf4e2b9dd84 / xfs defaults 0 0
10 UUID=ac6bb7e3-fa78-4eb2-b00d-e85c421c1bb0 /app xfs defaults 0 0
11 UUID=92886c3f-42a3-40f4-8cf7-c6890ca3a52e /boot xfs defaults 0 0
12 UUID=104520e1-0e97-4248-8fd0-a21e7d88a881 swap swap defaults 0 0
13 /dev/cdrom /mnt iso9660 defaults 0 0
[root@centos72 ~]# sed -n '9,+3p' /etc/fstab
UUID=5998ead0-b370-4859-9153-ecf4e2b9dd84 / xfs defaults 0 0
UUID=ac6bb7e3-fa78-4eb2-b00d-e85c421c1bb0 /app xfs defaults 0 0
UUID=92886c3f-42a3-40f4-8cf7-c6890ca3a52e /boot xfs defaults 0 0
UUID=104520e1-0e97-4248-8fd0-a21e7d88a881 swap swap defaults 0 0
注意只能+，不能-
[root@centos72 ~]# sed -n '9,-3p' /etc/fstab sed: -e expression #1, char 3: unexpected `,'
3）/pat1/,/pat2/ 打印两个模式之间的内容，也就要匹配两个条件
[root@centos72 ~]# sed '' /etc/passwd root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt mail:x:8:12:mail:/var/spool/mail:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin nobody:x:99:99:Nobody:/:/sbin/nologin systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin dbus:x:81:81:System message bus:/:/sbin/nologin polkitd:x:999:998:User for polkitd:/:/sbin/nologin sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin postfix:x:89:89::/var/spool/postfix:/sbin/nologin wang:x:1000:1000:wang:/home/wang:/bin/bash
b开头h结尾的行
[root@centos72 ~]# sed -n /^b/,/^h/p /etc/passwd bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt [root@centos72 ~]# sed -n '/^b/,/^h/p' /etc/passwd bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt
行以r开头u结尾，但是没有u结尾就打印到文件的最后一行
[root@centos72 ~]# cat /etc/passwd | sed -n '/^r/,/^u/p' root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt mail:x:8:12:mail:/var/spool/mail:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin nobody:x:99:99:Nobody:/:/sbin/nologin systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin dbus:x:81:81:System message bus:/:/sbin/nologin polkitd:x:999:998:User for polkitd:/:/sbin/nologin sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin postfix:x:89:89::/var/spool/postfix:/sbin/nologin wang:x:1000:1000:wang:/home/wang:/bin/bash
4）#,/pat1/
从第几行到匹配模式的行
[root@centos72 ~]# sed -n '6,/^u/p' /etc/passwd
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
polkitd:x:999:998:User for polkitd:/:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
wang:x:1000:1000:wang:/home/wang:/bin/bash
[root@centos72 ~]# cat -n /etc/passwd
1 root:x:0:0:root:/root:/bin/bash
2 bin:x:1:1:bin:/bin:/sbin/nologin
3 daemon:x:2:2:daemon:/sbin:/sbin/nologin
4 adm:x:3:4:adm:/var/adm:/sbin/nologin
5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
6 sync:x:5:0:sync:/sbin:/bin/sync
7 shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
8 halt:x:7:0:halt:/sbin:/sbin/halt
9 mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
10 operator:x:11:0:operator:/root:/sbin/nologin
11 games:x:12:100:games:/usr/games:/sbin/nologin
12 ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
13 nobody:x:99:99:Nobody:/:/sbin/nologin
14 systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
15 dbus:x:81:81:System message bus:/:/sbin/nologin
16 polkitd:x:999:998:User for polkitd:/:/sbin/nologin
17 sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
18 postfix:x:89:89::/var/spool/postfix:/sbin/nologin
19 wang:x:1000:1000:wang:/home/wang:/bin/bash
/pat/,#
[root@centos72 ~]# cat -n /etc/passwd
1 root:x:0:0:root:/root:/bin/bash
2 bin:x:1:1:bin:/bin:/sbin/nologin
3 daemon:x:2:2:daemon:/sbin:/sbin/nologin
4 adm:x:3:4:adm:/var/adm:/sbin/nologin
5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
6 sync:x:5:0:sync:/sbin:/bin/sync
7 shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
8 halt:x:7:0:halt:/sbin:/sbin/halt
9 mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
10 operator:x:11:0:operator:/root:/sbin/nologin
11 games:x:12:100:games:/usr/games:/sbin/nologin
12 ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
13 nobody:x:99:99:Nobody:/:/sbin/nologin
14 systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
15 dbus:x:81:81:System message bus:/:/sbin/nologin
16 polkitd:x:999:998:User for polkitd:/:/sbin/nologin
17 sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
18 postfix:x:89:89::/var/spool/postfix:/sbin/nologin
19 wang:x:1000:1000:wang:/home/wang:/bin/bash
[root@centos72 ~]# sed -n /^f/,+5p /etc/passwd
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
polkitd:x:999:998:User for polkitd:/:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
[root@centos72 ~]# sed -n /^f/,15p /etc/passwd
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
（4） ~：步进
1~2 奇数行，表示从第1行开始打印，每2行打印一次
2~2 偶数行，表示从第2行开始打印，每2行打印一次
1）打印文件的奇数行
[root@centos72 ~]# sed -n 1~2p /etc/passwd
root:x:0:0:root:/root:/bin/bash
daemon:x:2:2:daemon:/sbin:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
wang:x:1000:1000:wang:/home/wang:/bin/bash
[root@centos72 ~]# cat /etc/passwd -n | sed -n 1~2p
1 root:x:0:0:root:/root:/bin/bash
3 daemon:x:2:2:daemon:/sbin:/sbin/nologin
5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
7 shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
9 mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
11 games:x:12:100:games:/usr/games:/sbin/nologin
13 nobody:x:99:99:Nobody:/:/sbin/nologin
15 dbus:x:81:81:System message bus:/:/sbin/nologin
17 sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
19 wang:x:1000:1000:wang:/home/wang:/bin/bash
2）打印文件的偶数行
[root@centos72 ~]# cat /etc/passwd -n | sed -n 2~2p
2 bin:x:1:1:bin:/bin:/sbin/nologin
4 adm:x:3:4:adm:/var/adm:/sbin/nologin
6 sync:x:5:0:sync:/sbin:/bin/sync
8 halt:x:7:0:halt:/sbin:/sbin/halt
10 operator:x:11:0:operator:/root:/sbin/nologin
12 ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
14 systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
16 polkitd:x:999:998:User for polkitd:/:/sbin/nologin
18 postfix:x:89:89::/var/spool/postfix:/sbin/nologin
四编辑命令的使用
（一）d: 删除模式空间匹配的行，并立即启用下一轮循环
d: 删除模式空间匹配的行，并立即启用下一轮循环，也就是读入新的一行
（1）删除命令的第几行到第几行
删除文件的第6行到第16行
[root@centos72 ~]# cat /etc/passwd -n | sed 6,16d
1 root:x:0:0:root:/root:/bin/bash
2 bin:x:1:1:bin:/bin:/sbin/nologin
3 daemon:x:2:2:daemon:/sbin:/sbin/nologin
4 adm:x:3:4:adm:/var/adm:/sbin/nologin
5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
17 sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
18 postfix:x:89:89::/var/spool/postfix:/sbin/nologin
19 wang:x:1000:1000:wang:/home/wang:/bin/bash
（2）利用删除命令打印奇数行，也就是把偶数行删除了
法1：
[root@centos72 ~]# cat /etc/passwd -n | sed -n 1~2p
1 root:x:0:0:root:/root:/bin/bash
3 daemon:x:2:2:daemon:/sbin:/sbin/nologin
5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
7 shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
9 mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
11 games:x:12:100:games:/usr/games:/sbin/nologin
13 nobody:x:99:99:Nobody:/:/sbin/nologin
15 dbus:x:81:81:System message bus:/:/sbin/nologin
17 sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
19 wang:x:1000:1000:wang:/home/wang:/bin/bash
法2：
[root@centos72 ~]# cat /etc/passwd -n | sed -n 2~2d
[root@centos72 ~]# cat /etc/passwd -n | sed 2~2d 1 root:x:0:0:root:/root:/bin/bash 3 daemon:x:2:2:daemon:/sbin:/sbin/nologin 5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin 7 shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown 9 mail:x:8:12:mail:/var/spool/mail:/sbin/nologin 11 games:x:12:100:games:/usr/games:/sbin/nologin 13 nobody:x:99:99:Nobody:/:/sbin/nologin 15 dbus:x:81:81:System message bus:/:/sbin/nologin 17 sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin 19 wang:x:1000:1000:wang:/home/wang:/bin/bash
（3）把标准输入指定行删除
显示网络状态信息
[root@centos72 ~]# ss -tnl State Recv-Q Send-Q Local Address:Port Peer Address:Port LISTEN 0 128 *:22 *:* LISTEN 0 100 127.0.0.1:25 *:* LISTEN 0 128 :::22 :::* LISTEN 0 100 ::1:25 :::*
删除网络状态信息的第1行
命令可以不加引号
[root@centos72 ~]# ss -tnl | sed 1d
LISTEN 0 128 *:22 *:* LISTEN 0 100 127.0.0.1:25 *:* LISTEN 0 128 :::22 :::* LISTEN 0 100 ::1:25 :::*
[root@centos72 ~]# ss -tnl | sed '1d' LISTEN 0 128 *:22 *:* LISTEN 0 100 127.0.0.1:25 *:* LISTEN 0 128 :::22 :::* LISTEN 0 100 ::1:25 :::*
打印以sd开头的内容
/是进行模式匹配的，和/dev里面的斜线冲突，所以要对非模式匹配的斜线进行转义
注意打印时最好都加上引号，否则会报错
[root@centos72 ~]# df | sed -n /^\/dev\/sd/p sed: -e expression #1, char 5: extra characters after command [root@centos72 ~]# df | sed -n '/^\/dev\/sd/p' /dev/sda2 52403200 1119724 51283476 3% / /dev/sda3 20961280 32944 20928336 1% /app /dev/sda1 1038336 126596 911740 13% /boot
如果不转义就会报错
/pattern/：被此处模式所能够匹配到的每一行
[root@centos72 ~]# df | sed -n '/^/dev/sd/p' sed: -e expression #1, char 5: extra characters after command
不可以使用其他符合进行分隔
[root@centos73 ~]# df | sed -n '#^/dev/sd#p' [root@centos73 ~]# df | sed -n '#^/dev/sd#p'
（二）a [\]text：在指定行后面追加文本，支持使用\n实现多行追加
（1）在文件的第5行到第10行的每行的下一行添加&&&&&&&&&
[root@centos72 ~]# cat -n /etc/passwd | sed '5,10a&&&&&&&&&'
1 root:x:0:0:root:/root:/bin/bash
2 bin:x:1:1:bin:/bin:/sbin/nologin
3 daemon:x:2:2:daemon:/sbin:/sbin/nologin
4 adm:x:3:4:adm:/var/adm:/sbin/nologin
5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
&&&&&&&&&
6 sync:x:5:0:sync:/sbin:/bin/sync
&&&&&&&&&
7 shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
&&&&&&&&&
8 halt:x:7:0:halt:/sbin:/sbin/halt
&&&&&&&&&
9 mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
&&&&&&&&&
10 operator:x:11:0:operator:/root:/sbin/nologin
&&&&&&&&&
11 games:x:12:100:games:/usr/games:/sbin/nologin
12 ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
13 nobody:x:99:99:Nobody:/:/sbin/nologin
14 systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
15 dbus:x:81:81:System message bus:/:/sbin/nologin
16 polkitd:x:999:998:User for polkitd:/:/sbin/nologin
17 sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
18 postfix:x:89:89::/var/spool/postfix:/sbin/nologin
19 wang:x:1000:1000:wang:/home/wang:/bin/bash
注意 一定要加引号
[root@centos65 ~]# cat -n /etc/passwd | sed 5,10a&&&&&&&&&
-bash: syntax error near unexpected token `&&'
双引号也可以
[root@centos65 ~]# cat -n /etc/passwd | sed "5,10a&&&&&&&&&" 1 root:x:0:0:root:/root:/bin/bash 2 bin:x:1:1:bin:/bin:/sbin/nologin 3 daemon:x:2:2:daemon:/sbin:/sbin/nologin 4 adm:x:3:4:adm:/var/adm:/sbin/nologin 5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin &&&&&&&&& 6 sync:x:5:0:sync:/sbin:/bin/sync &&&&&&&&& 7 shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown &&&&&&&&& 8 halt:x:7:0:halt:/sbin:/sbin/halt &&&&&&&&& 9 mail:x:8:12:mail:/var/spool/mail:/sbin/nologin &&&&&&&&& 10 uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin &&&&&&&&& 11 operator:x:11:0:operator:/root:/sbin/nologin 12 games:x:12:100:games:/usr/games:/sbin/nologin 13 gopher:x:13:30:gopher:/var/gopher:/sbin/nologin 14 ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin 15 nobody:x:99:99:Nobody:/:/sbin/nologin 16 vcsa:x:69:69:virtual console memory owner:/dev:/sbin/nologin 17 saslauth:x:499:76:Saslauthd user:/var/empty/saslauth:/sbin/nologin 18 postfix:x:89:89::/var/spool/postfix:/sbin/nologin 19 sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin 20 dbus:x:81:81:System message bus:/:/sbin/nologin 21 ntp:x:38:38::/etc/ntp:/sbin/nologin 22 abrt:x:173:173::/etc/abrt:/sbin/nologin 23 haldaemon:x:68:68:HAL daemon:/:/sbin/nologin 24 tcpdump:x:72:72::/:/sbin/nologin 25 rpc:x:32:32:Rpcbind Daemon:/var/lib/rpcbind:/sbin/nologin 26 rpcuser:x:29:29:RPC Service User:/var/lib/nfs:/sbin/nologin 27 nfsnobody:x:65534:65534:Anonymous NFS User:/var/lib/nfs:/sbin/nologin 28 radvd:x:75:75:radvd user:/:/sbin/nologin 29 qemu:x:107:107:qemu user:/:/sbin/nologin 30 ident:x:98:98::/:/sbin/nologin
原文件的内容没有真正被修改
[root@centos72 ~]# cat /etc/passwd -n
1 root:x:0:0:root:/root:/bin/bash 2 bin:x:1:1:bin:/bin:/sbin/nologin 3 daemon:x:2:2:daemon:/sbin:/sbin/nologin 4 adm:x:3:4:adm:/var/adm:/sbin/nologin 5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin 6 sync:x:5:0:sync:/sbin:/bin/sync 7 shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown 8 halt:x:7:0:halt:/sbin:/sbin/halt 9 mail:x:8:12:mail:/var/spool/mail:/sbin/nologin 10 operator:x:11:0:operator:/root:/sbin/nologin 11 games:x:12:100:games:/usr/games:/sbin/nologin 12 ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin 13 nobody:x:99:99:Nobody:/:/sbin/nologin 14 systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin 15 dbus:x:81:81:System message bus:/:/sbin/nologin 16 polkitd:x:999:998:User for polkitd:/:/sbin/nologin 17 sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin 18 postfix:x:89:89::/var/spool/postfix:/sbin/nologin 19 wang:x:1000:1000:wang:/home/wang:/bin/bash
（2）命令和文件之间有没有空格显示的结果都一样的。
[root@centos72 ~]# cat -n /etc/passwd | sed '5,10a &&&&&&&&&'
1 root:x:0:0:root:/root:/bin/bash
2 bin:x:1:1:bin:/bin:/sbin/nologin
3 daemon:x:2:2:daemon:/sbin:/sbin/nologin
4 adm:x:3:4:adm:/var/adm:/sbin/nologin
5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
&&&&&&&&&
6 sync:x:5:0:sync:/sbin:/bin/sync
&&&&&&&&&
7 shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
&&&&&&&&&
8 halt:x:7:0:halt:/sbin:/sbin/halt
&&&&&&&&&
9 mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
&&&&&&&&&
10 operator:x:11:0:operator:/root:/sbin/nologin
&&&&&&&&&
11 games:x:12:100:games:/usr/games:/sbin/nologin
12 ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
13 nobody:x:99:99:Nobody:/:/sbin/nologin
14 systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
15 dbus:x:81:81:System message bus:/:/sbin/nologin
16 polkitd:x:999:998:User for polkitd:/:/sbin/nologin
17 sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
18 postfix:x:89:89::/var/spool/postfix:/sbin/nologin
19 wang:x:1000:1000:wang:/home/wang:/bin/bash
[root@centos72 ~]# cat -n /etc/passwd | sed '5,10 a&&&&&&&&&'
1 root:x:0:0:root:/root:/bin/bash
2 bin:x:1:1:bin:/bin:/sbin/nologin
3 daemon:x:2:2:daemon:/sbin:/sbin/nologin
4 adm:x:3:4:adm:/var/adm:/sbin/nologin
5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
&&&&&&&&&
6 sync:x:5:0:sync:/sbin:/bin/sync
&&&&&&&&&
7 shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
&&&&&&&&&
8 halt:x:7:0:halt:/sbin:/sbin/halt
&&&&&&&&&
9 mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
&&&&&&&&&
10 operator:x:11:0:operator:/root:/sbin/nologin
&&&&&&&&&
11 games:x:12:100:games:/usr/games:/sbin/nologin
12 ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
13 nobody:x:99:99:Nobody:/:/sbin/nologin
14 systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
15 dbus:x:81:81:System message bus:/:/sbin/nologin
16 polkitd:x:999:998:User for polkitd:/:/sbin/nologin
17 sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
18 postfix:x:89:89::/var/spool/postfix:/sbin/nologin
19 wang:x:1000:1000:wang:/home/wang:/bin/bash
（3）如果要想打印出空格的，那么就要a后面加上斜线，斜线就相当于边界符
[\]表示此选项可有可无
[root@centos72 ~]# cat -n /etc/passwd | sed '5,10a\ &&&&&&&&&'
1 root:x:0:0:root:/root:/bin/bash
2 bin:x:1:1:bin:/bin:/sbin/nologin
3 daemon:x:2:2:daemon:/sbin:/sbin/nologin
4 adm:x:3:4:adm:/var/adm:/sbin/nologin
5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
&&&&&&&&&
6 sync:x:5:0:sync:/sbin:/bin/sync
&&&&&&&&&
7 shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
&&&&&&&&&
8 halt:x:7:0:halt:/sbin:/sbin/halt
&&&&&&&&&
9 mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
&&&&&&&&&
10 operator:x:11:0:operator:/root:/sbin/nologin
&&&&&&&&&
11 games:x:12:100:games:/usr/games:/sbin/nologin
12 ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
13 nobody:x:99:99:Nobody:/:/sbin/nologin
14 systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
15 dbus:x:81:81:System message bus:/:/sbin/nologin
16 polkitd:x:999:998:User for polkitd:/:/sbin/nologin
17 sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
18 postfix:x:89:89::/var/spool/postfix:/sbin/nologin
19 wang:x:1000:1000:wang:/home/wang:/bin/bash
注意斜线要和后面的内容有空格，至少是一个空格
[root@centos72 ~]# cat -n /etc/passwd | sed '5,10a \&&&&&&&&&'
1 root:x:0:0:root:/root:/bin/bash
2 bin:x:1:1:bin:/bin:/sbin/nologin
3 daemon:x:2:2:daemon:/sbin:/sbin/nologin
4 adm:x:3:4:adm:/var/adm:/sbin/nologin
5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
&&&&&&&&&
6 sync:x:5:0:sync:/sbin:/bin/sync
&&&&&&&&&
7 shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
&&&&&&&&&
8 halt:x:7:0:halt:/sbin:/sbin/halt
&&&&&&&&&
9 mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
&&&&&&&&&
10 operator:x:11:0:operator:/root:/sbin/nologin
&&&&&&&&&
11 games:x:12:100:games:/usr/games:/sbin/nologin
12 ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
13 nobody:x:99:99:Nobody:/:/sbin/nologin
14 systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
15 dbus:x:81:81:System message bus:/:/sbin/nologin
16 polkitd:x:999:998:User for polkitd:/:/sbin/nologin
17 sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
18 postfix:x:89:89::/var/spool/postfix:/sbin/nologin
19 wang:x:1000:1000:wang:/home/wang:/bin/bash
[root@centos72 ~]# cat -n /etc/passwd | sed '5,10a \ &&&&&&&&&'
1 root:x:0:0:root:/root:/bin/bash
2 bin:x:1:1:bin:/bin:/sbin/nologin
3 daemon:x:2:2:daemon:/sbin:/sbin/nologin
4 adm:x:3:4:adm:/var/adm:/sbin/nologin
5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
&&&&&&&&&
6 sync:x:5:0:sync:/sbin:/bin/sync
&&&&&&&&&
7 shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
&&&&&&&&&
8 halt:x:7:0:halt:/sbin:/sbin/halt
&&&&&&&&&
9 mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
&&&&&&&&&
10 operator:x:11:0:operator:/root:/sbin/nologin
&&&&&&&&&
11 games:x:12:100:games:/usr/games:/sbin/nologin
12 ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
13 nobody:x:99:99:Nobody:/:/sbin/nologin
14 systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
15 dbus:x:81:81:System message bus:/:/sbin/nologin
16 polkitd:x:999:998:User for polkitd:/:/sbin/nologin
17 sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
18 postfix:x:89:89::/var/spool/postfix:/sbin/nologin
19 wang:x:1000:1000:wang:/home/wang:/bin/bash
实例：
在第8行之后追加
现在只是显示，没有真正追加到文件里面
因为模式匹配是单引号，所以里面的追加内容只能使用双引号，否则会引起冲突的
[root@centos72 ~]# sed '8a alias cdne="cd /etc/sysconfig/network-scripts/"' ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'
alias cdne="cd /etc/sysconfig/network-scripts/"
# Source global definitions
if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi
原文件内容保持不变
第8行是空行
[root@centos72 ~]# cat -n ~/.bashrc
1 # .bashrc
2
3 # User specific aliases and functions 4 5 alias rm='rm -i' 6 alias cp='cp -i' 7 alias mv='mv -i' 8 9 # Source global definitions 10 if [ -f /etc/bashrc ]; then 11 . /etc/bashrc 12 fi
（三）-i.bak: 备份文件并原处编辑
真正追加到文件里面，要谨慎使用，确定没有问题再确定追加，凡事三思而后行。
-i.bak: 备份文件并原处编辑，也就是先对原来的文件进行备份再修改，这样会更好。
我们在对某个服务的配置文件进行修改时也要养成这种好习惯，先备份再修改，运维工作最重要的是备份。
如果是追加到文件的最后一行，使用echo重定向就可以了
[root@centos72 ~]# sed -i.bak '8a alias cdne="cd /etc/sysconfig/network-scripts/"' ~/.bashrc
[root@centos72 ~]# cat -n ~/.bashrc
1 # .bashrc
2
3 # User specific aliases and functions
4
5 alias rm='rm -i'
6 alias cp='cp -i'
7 alias mv='mv -i'
8
9 alias cdne="cd /etc/sysconfig/network-scripts/"
10 # Source global definitions
11 if [ -f /etc/bashrc ]; then
12 . /etc/bashrc
13 fi
[root@centos72 ~]# ls -a ~/
. .. anaconda-ks.cfg .bash_history .bash_logout .bash_profile .bashrc .bashrc.bak .cshrc .tcshrc .viminfo
#生成了备份文件.bashrc.bak
（四）i [\]text：在匹配的行前面插入文本
和a命令作用相似，结果相反。
使用到正则表达式，^表示行首
/^# Source/模式匹配，表示以# Source开头的行
[root@centos72 ~]# sed -i.bak '/^# Source/i$$$$$$$' ~/.bashrc
[root@centos72 ~]# cat -n ~/.bashrc
1 # .bashrc
2
3 # User specific aliases and functions
4
5 alias rm='rm -i'
6 alias cp='cp -i'
7 alias mv='mv -i'
8
9 alias cdne="cd /etc/sysconfig/network-scripts/"
10 $$$$$$$
11 # Source global definitions
12 if [ -f /etc/bashrc ]; then
13 . /etc/bashrc
14 fi
和a一样，如果\和后面的文本没有空格那么和没加\是一样的结果
[root@centos72 ~]# sed '/^# Source/i\**********' ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'
alias cdne="cd /etc/sysconfig/network-scripts/"
$$$$$$$
**********
# Source global definitions
if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi
[root@centos72 ~]# sed '/^# Source/i\ **********' ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'
alias cdne="cd /etc/sysconfig/network-scripts/"
$$$$$$$
**********
# Source global definitions
if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi
[root@centos65 ~]# sed '/^# Source/i\ **********' ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' ********** # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi
对比：
a是在行后追加
[root@centos72 ~]# sed '/^# Source/a**********' ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'
alias cdne="cd /etc/sysconfig/network-scripts/"
$$$$$$$
# Source global definitions
**********
if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi
[root@centos72 ~]# sed '/^# Source/a\**********' ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'
alias cdne="cd /etc/sysconfig/network-scripts/"
$$$$$$$
# Source global definitions
**********
if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi
[root@centos72 ~]# sed '/^# Source/a \ **********' ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'
alias cdne="cd /etc/sysconfig/network-scripts/"
$$$$$$$
# Source global definitions
**********
if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi
实现多行追加
这样就可以一次性加好几条别名
[root@centos72 ~]# cat ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' alias cdne="cd /etc/sysconfig/network-scripts/" $$$$$$$ # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi [root@centos72 ~]# sed '/^# Source/ixxxxxxxxxxxx\nyyyyyyyyyy\nzzzzzzzzzzzzz' ~/.bashrc # .bashrc # User specific aliases and functions alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' alias cdne="cd /etc/sysconfig/network-scripts/" $$$$$$$ xxxxxxxxxxxx yyyyyyyyyy zzzzzzzzzzzzz # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi
注意此时的家目录是root
所以~/.bashrc和/root/.bashrc是等价的
[root@centos72 ~]# cat ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' alias ka='systemctl restart keepalived.service' # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi [root@centos72 ~]# pwd /root [root@centos72 ~]# cat /root/.bashrc # .bashrc # User specific aliases and functions alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' alias ka='systemctl restart keepalived.service' # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi
[root@centos65 ~]# diff /root/.bashr^C ~/.bashrc
[root@centos65 ~]# who
root pts/0 2019-01-25 05:32 (192.168.137.1) [root@centos65 ~]# whoami root
（五）c [\]text：替换行为单行或多行文本
[root@centos72 ~]# cat -n ~/.bashrc
1 # .bashrc
2
3 # User specific aliases and functions
4
5 alias rm='rm -i'
6 alias cp='cp -i'
7 alias mv='mv -i'
8
9 alias cdne="cd /etc/sysconfig/network-scripts/"
10 $$$$$$$
11 # Source global definitions
12 if [ -f /etc/bashrc ]; then
13 . /etc/bashrc
14 fi
[root@centos72 ~]# sed '/^# Source/c \ **********' ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'
alias cdne="cd /etc/sysconfig/network-scripts/"
$$$$$$$
**********
if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi
[root@centos72 ~]# sed '/^# Source/c **********' ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'
alias cdne="cd /etc/sysconfig/network-scripts/"
$$$$$$$
**********
if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi
[root@centos65 ~]# cat ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi
[root@centos65 ~]# sed '/^# Source/c **********' ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' ********** if [ -f /etc/bashrc ]; then . /etc/bashrc fi [root@centos65 ~]# cat ~/.bashrc # .bashrc # User specific aliases and functions alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi
实例：
（1）实现一行替换
替换的很实用，特别是在修改配置文件的时候
/pattern/：被此处模式所能够匹配到的每一行
# This file controls the state of SELinux on the system. # SELINUX= can take one of these three values: # enforcing - SELinux security policy is enforced. # permissive - SELinux prints warnings instead of enforcing. # disabled - No SELinux policy is loaded. SELINUX=enforcing # SELINUXTYPE= can take one of three two values: # targeted - Targeted processes are protected, # minimum - Modification of targeted policy. Only selected processes are protected. # mls - Multi Level Security protection. SELINUXTYPE=targeted [root@centos72 ~]# sed -i.bak '/^SELINUX=/c SELINUX=disabled' /etc/selinux/config [root@centos72 ~]# cat /etc/selinux/config # This file controls the state of SELinux on the system. # SELINUX= can take one of these three values: # enforcing - SELinux security policy is enforced. # permissive - SELinux prints warnings instead of enforcing. # disabled - No SELinux policy is loaded. SELINUX=disabled # SELINUXTYPE= can take one of three two values: # targeted - Targeted processes are protected, # minimum - Modification of targeted policy. Only selected processes are protected. # mls - Multi Level Security protection. SELINUXTYPE=targeted
/^SELINUX=/表示匹配以SELINUX=开头的行
[root@centos65 ~]# cat /etc/selinux/config
# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
# enforcing - SELinux security policy is enforced. # permissive - SELinux prints warnings instead of enforcing. # disabled - No SELinux policy is loaded. SELINUX=enforcing # SELINUXTYPE= can take one of these two values: # targeted - Targeted processes are protected, # mls - Multi Level Security protection. SELINUXTYPE=targeted [root@centos65 ~]# #sed '/^SELINUX=/c SELINUX=disabled' /etc/selinux/config [root@centos65 ~]# sed '/^SELINUX=/c SELINUX=disabled' /etc/selinux/config # This file controls the state of SELinux on the system. # SELINUX= can take one of these three values: # enforcing - SELinux security policy is enforced. # permissive - SELinux prints warnings instead of enforcing. # disabled - No SELinux policy is loaded. SELINUX=disabled # SELINUXTYPE= can take one of these two values: # targeted - Targeted processes are protected, # mls - Multi Level Security protection. SELINUXTYPE=targeted
（六）w /path/somefile: 保存模式匹配的行至指定文件
w /path/somefile: 保存模式匹配的行至指定文件，要加上单引号才可以
[root@centos72 ~]# sed /^alias/w /app/alias.txt
sed: couldn't open file : No such file or directory [root@centos72 ~]# sed /^alias/w /app/alias.txt ~/.bashrc sed: couldn't open file : No such file or directory [root@centos72 ~]# sed '/^alias/w /app/alias.txt' ~/.bashrc # .bashrc # User specific aliases and functions alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' alias cdne="cd /etc/sysconfig/network-scripts/" $$$$$$$ # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi
执行结果，下面是自动创建的文件
[root@centos72 ~]# cat /app/alias.txt
alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' alias ka='systemctl restart keepalived.service'
也就是把最后的文件匹配到的内容复制到中间指定的文件
[root@centos73 ~]# sed '/^alias/w /app/alias.txt' ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi [root@centos73 ~]# cat /app/alias.txt' > ^C [root@centos73 ~]# cat /app/alias.txt alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' [root@centos73 ~]# ll /app/alias.txt -rw-r--r--. 1 root root 51 Jun 20 14:07 /app/alias.txt
使用双引号也可以
和变量一样要加引号
[root@centos72 ~]# sed "/^alias/w /app/as.txt" ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' alias ka='systemctl restart keepalived.service' # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi [root@centos72 ~]# cat /app/a alias.txt as.txt [root@centos72 ~]# cat /app/as.txt alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' alias ka='systemctl restart keepalived.service'
（七）r /path/somefile：读取指定文件的文本至模式空间中匹配到的行后
在alias开头的行后面追加文件的内容
[root@centos72 ~]# sed '/^alias/r /etc/centos-release' ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i' CentOS Linux release 7.5.1804 (Core) alias cp='cp -i' CentOS Linux release 7.5.1804 (Core) alias mv='mv -i' CentOS Linux release 7.5.1804 (Core) alias cdne="cd /etc/sysconfig/network-scripts/" CentOS Linux release 7.5.1804 (Core) $$$$$$$ # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi
=: 为模式空间中的行打印行号
[root@centos72 ~]# sed '/^alias/=' ~/.bashrc
# .bashrc
# User specific aliases and functions
5 alias rm='rm -i' 6 alias cp='cp -i' 7 alias mv='mv -i' 9 alias cdne="cd /etc/sysconfig/network-scripts/" $$$$$$$ # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi [root@centos72 ~]# cat -n .bashrc 1 # .bashrc 2 3 # User specific aliases and functions 4 5 alias rm='rm -i' 6 alias cp='cp -i' 7 alias mv='mv -i' 8 9 alias cdne="cd /etc/sysconfig/network-scripts/" 10 $$$$$$$ 11 # Source global definitions 12 if [ -f /etc/bashrc ]; then 13 . /etc/bashrc 14 fi
（八）!:模式空间中匹配行取反处理
在条件测试里面！也表示取反
[root@centos72 ~]# sed '/^alias/p' ~/.bashrc
# .bashrc
# User specific aliases and functions
alias rm='rm -i' alias rm='rm -i' alias cp='cp -i' alias cp='cp -i' alias mv='mv -i' alias mv='mv -i' alias cdne="cd /etc/sysconfig/network-scripts/" alias cdne="cd /etc/sysconfig/network-scripts/" $$$$$$$ # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi
注意！只能加在命令的前面
[root@centos72 ~]# sed '/^alias/p!' ~/.bashrc
sed: -e expression #1, char 10: extra characters after command [root@centos72 ~]# sed '/^alias/!p' ~/.bashrc # .bashrc # .bashrc # User specific aliases and functions # User specific aliases and functions alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' alias cdne="cd /etc/sysconfig/network-scripts/" $$$$$$$ $$$$$$$ # Source global definitions # Source global definitions if [ -f /etc/bashrc ]; then if [ -f /etc/bashrc ]; then . /etc/bashrc . /etc/bashrc fi fi
取反之后就不打印alias开头的行了
[root@centos72 ~]# sed -n '/^alias/p' ~/.bashrc
alias rm='rm -i' alias cp='cp -i' alias mv='mv -i' alias cdne="cd /etc/sysconfig/network-scripts/" [root@centos72 ~]# sed -n '/^alias/!p' ~/.bashrc # .bashrc # User specific aliases and functions $$$$$$$ # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi
显示文件中以bash结尾的行，涉及到正则表达式$
[root@centos72 ~]# sed -n '/bash$/p' /etc/passwd root:x:0:0:root:/root:/bin/bash wang:x:1000:1000:wang:/home/wang:/bin/bash [root@centos72 ~]# cat /etc/passwd root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt mail:x:8:12:mail:/var/spool/mail:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin nobody:x:99:99:Nobody:/:/sbin/nologin systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin dbus:x:81:81:System message bus:/:/sbin/nologin polkitd:x:999:998:User for polkitd:/:/sbin/nologin sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin postfix:x:89:89::/var/spool/postfix:/sbin/nologin wang:x:1000:1000:wang:/home/wang:/bin/bash
打印除bash结尾的行
[root@centos72 ~]# sed -n '/bash$/!p' /etc/passwd bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt mail:x:8:12:mail:/var/spool/mail:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin nobody:x:99:99:Nobody:/:/sbin/nologin systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin dbus:x:81:81:System message bus:/:/sbin/nologin polkitd:x:999:998:User for polkitd:/:/sbin/nologin sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin postfix:x:89:89::/var/spool/postfix:/sbin/nologin