1.利用sed 取出ifconfig命令中本机的IPv4地址

[root@www ~]# ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.88.11  netmask 255.255.255.0  broadcast 192.168.88.255
        inet6 fe80::6dbe:4358:4300:f8ea  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:e9:6d:c7  txqueuelen 1000  (Ethernet)
        RX packets 69455  bytes 37222875 (35.4 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 61421  bytes 48707792 (46.4 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[root@www ~]# ifconfig eth0|sed -nr '2s#inet +([0-9.]+{4}).*#\1#p'
        192.168.88.11

2.删除/etc/fstab文件中所有以#开头，后面至少跟一个空白字符的行的行首的#和空白字符

[root@www ~]# sed -rn 's@^# +(.*)@\1@p'   /etc/fstab
/etc/fstab$
Created by anaconda on Sat Nov 14 10:11:08 2020$
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$

[root@www ~]# awk '/^# +.*/{$1="";print $0}'  /etc/fstab     #$1赋值空，打印空列
 /etc/fstab
 Created by anaconda on Sat Nov 14 10:11:08 2020
 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

3.处理/etc/fstab路径,使用sed命令取出其目录名和基名

 ls /etc/sysconfig/network-scripts/ifcfg-eth0  | sed -nr  's#(.*\/)(.*)#\1\n\2#p'