7.4任务(shell命令sed)

9.4 sed(上)
过滤字符：

[root@localhost sed]# sed -n '/root/'p passwd
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin

也支持“.” “*”的匹配：

[root@localhost sed]# sed -n '/r.t/'p passwd
operator:x:11:0:operator:/root:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
[root@localhost sed]# sed -n '/r*t/'p passwd
root:x:0:0:root:/root:/bin/bash
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
operator:x:11:0:operator:/root:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
polkitd:x:999:997:User for polkitd:/:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
haha:x:1007:1005::/home/test:/sbin/nologin
test1:x:1100:1009::/home/test1:/bin/bash
saslauth:x:997:76:Saslauthd user:/run/saslauthd:/sbin/nologin

还有“+”的匹配：不过“+”符号需要转义，或者使用-r选项就不需要转义了。两者都没有，则无法匹配到内容。

[root@localhost sed]# sed -n '/o\+t/'p passwd
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin
[root@localhost sed]# sed -nr '/o+t/'p passwd
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin

相同字符匹配多次：

[root@localhost sed]# sed -nr '/o{2}/'p passwd
root:x:0:0:root:/root:/bin/bash
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin

或者选项：

[root@localhost sed]# sed -nr '/root|bus/'p passwd
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin

sed下
查看具体某行的内容：

[root@localhost sed]# sed -n '2'p passwd
bin:x:1:1:bin:/bin:/sbin/nologin
[root@localhost sed]# sed -n '13'p passwd
nobody:x:99:99:Nobody:/:/sbin/nologin
[root@localhost sed]# sed -n '1,3'p 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
[root@localhost sed]# sed -n '29,$'p passwd
aiya:x:1102:1102::/www/aiya:/sbin/nologin
dhcpd:x:177:177:DHCP server:/:/sbin/nologin
saslauth:x:997:76:Saslauthd user:/run/saslauthd:/sbin/nologin

同时完成两个操作：当两个内容想重合，那么会重复两次：

[root@localhost sed]# sed -e '1'p -e '/bus/'p -n passwd
root:x:0:0:root:/root:/bin/bash
dbus:x:81:81:System message bus:/:/sbin/nologin

内容重合：

[root@localhost sed]# sed -e '1'p -e '/root/'p -n passwd
root:x:0:0:root:/root:/bin/bash
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin

“*”星号通配符：

[root@localhost sed]# sed -n '/roo*/'p passwd    //有ro即可。
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin
chrony:x:998:996::/var/lib/chrony:/sbin/nologin