文本处理工具——sed基础

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 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 
 on an m
Kernel 
 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 
 on an m
Kernel 
 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 
 on an m

[root@centos72 ~]# sed    -n   'p'   /etc/issue  
S
Kernel 
 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 
 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 
 on an m
Kernel 
 on an m

[root@centos72 ~]# sed    -n   '2p'   /etc/issue  
Kernel 
 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 
 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 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
yyyyyyyyyy
zzzzzzzzzzzzz'    ~/.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