sed 命令

参考：http://man.linuxde.net/sed

1.截取指定内容

s为搜索

s/A/B/ 表示将A替换成B，且只替换一次，s/A/B/g 加上g表示全部替换，下面为将搜索到的内容替换成空格。

[root@sesprd tmp]# ifconfig eno16780032 | grep 'inet' | sed 's/^.*inet?//g'
        inet 10.1.1.179  netmask 255.255.255.0  broadcast 10.1.1.255
        inet6 fe80::250:56ff:fe8a:58e3  prefixlen 64  scopeid 0x20<link>
[root@sesprd tmp]# ifconfig eno16780032 | grep 'inet[^6]' | sed 's/^.*inet//g'
 10.1.1.179  netmask 255.255.255.0  broadcast 10.1.1.255
[root@sesprd tmp]# ifconfig eno16780032 | grep 'inet[^6]' | sed 's/^.*inet//g' | sed 's/netmask.*$//g'
 10.1.1.179  

注意点。sed -i 会真正改变源文件内容

#源文件内容
[root@sesprd tmp]# nl testsed
     1    hello
     2    I want to go to work
     3    doing working make me happy
     4    I  want to study linux well
[root@sesprd tmp]# ^C
#第一行后追加内容
[root@sesprd tmp]# sed '1a my name is gang' testsed
hello
my name is gang
I want to go to work
doing working make me happy
I  want to study linux well
#在第一行和第二行之后分别追加内容
root@sesprd tmp]# sed '1,2a come from jiangxi' testsed
hello
come from jiangxi
I want to go to work
come from jiangxi
doing working make me happy
I  want to study linux well
#删除第2行
[root@sesprd tmp]# sed '2d' testsed | nl
     1    hello
     2    doing working make me happy
     3    I  want to study linux well
#将第一行替换成hi
[root@sesprd tmp]# sed '1c hi' testsed | nl
     1    hi
     2    I want to go to work
     3    doing working make me happy
     4    I  want to study linux well
#第一行和第二行替换成hi
[root@sesprd tmp]# sed '1,2c hi' testsed | nl
     1    hi
     2    doing working make me happy
     3    I  want to study linux well
#在最后一行之前插入let ,之后插入$i改成$a
[root@sesprd tmp]# sed -i '$i let' testsed
[root@sesprd tmp]# cat -n testsed
     1    hello
     2    I want to go to work
     3    let
     4    doing working make me happy
#删除文件中以h或l开头的所有行

[root@sesprd tmp]# sed '/^[hl]/d' testsed
I want to go to work
doing working make me happy

#删除内容为/的行

[root@sesprd tmp]# nl testsed
1 hello
2 /
3 I want to go to work
4 /
5 let
6 /
7 doing working make me happy
8 /

[root@sesprd tmp]# sed -i '///d' testsed
[root@sesprd tmp]# nl testsed
1 hello
2 I want to go to work
3 let
4 doing working make me happy
[root@sesprd tmp]#

#删除空行

[root@sesprd tmp]# nl testsed
1 hello

2 I want to go to work

3 let

4 doing working make me happy

[root@sesprd tmp]#

#删除空行
[root@sesprd tmp]# sed -i '/^$/d' testsed

[root@sesprd tmp]# nl testsed
1 hello
2 I want to go to work
3 let
4 doing working make me happy

#最后一行添加空行

[root@sesprd tmp]# sed '$G' testsed
hello
I want to go to work
let
doing working make me happy

[root@sesprd tmp]# nl testsed

#最后一行添加内容

[root@sesprd tmp]# sed '$a last' testsed
hello
I want to go to work
let
doing working make me happy
last

#删除空格

[root@sesprd tmp]# sed 's/[[:space:]]*//g' testsed
hello
Iwanttogotowork
let
doingworkingmakemehappy

#将第一行字符之间的空格移除

[root@sesprd tmp]# sed -i '1s/[[:space:]]//g' testsed
[root@sesprd tmp]# nl testsed
1 hello
2 I want to go to work
3 let
4 doing working make me happy

#-n 仅显示处理后的结果 获取hello的下一行

[root@sesprd tmp]# sed -n '/^hell/{n;p}' testsed
I want to go to work
[root@sesprd tmp]#

#如果hello被匹配，则移动到匹配行的下一行，替换这一行的want，变为wt，并打印该行，然后继续：

[root@sesprd tmp]# sed '/hello/{ n; s/want/wt/; }' testsed
hello
I wt to go to work
let
doing working make me happy
[root@sesprd tmp]#

#将testsed文件中所有包含hel的行内容写入tt档案

[root@sesprd tmp]# sed '/hel/w tt' testsed
hello
I want to go to work
let
doing working make me happy
[root@sesprd tmp]# nl tt
1 hello
[root@sesprd tmp]#

#testsed里的内容被读进来，显示在与hel匹配的行后面，如果匹配多行，则tt的内容将显示在所有匹配行的下面

[root@sesprd tmp]# sed '/hel/r tt' testsed
hello
hello
I want to go to work
let
doing working make me happy
[root@sesprd tmp]#

-e选项允许在同一行里执行多条命令：

eg: sed -e '1,5d' -e 's/test/check/' file

#打印从第1行开始到第一个包含以le开始的行之间的所有行：

[root@sesprd tmp]# sed -n '1,/^le/p' testsed
hello
I want to go to work
let

显示文件X行到Y行的内容：

#sed -n 'x,yp' filename