【04-04】 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
# 备份文件到root家目录做测试
[root@centos-7 ~]# cp /etc/fstab /root/fstab
#查看该文件
[root@centos-7 ~]# cat /root/fstab
#
# /etc/fstab
# Created by anaconda on Thu Mar 7 06:38:37 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=4b499d76-769a-40a0-93dc-4a31a59add28 / ext4 defaults 1 1
#对文件进行处理 /^# 取得各行已#开头的行后传递给 s进行替换 s/^#// 替换为空后进行对文件修改
[root@centos-7 ~]# sed -ri.bak '/^#/s/^#//' /root/fstab
[root@centos-7 ~]# cat /root/fstab
/etc/fstab
Created by anaconda on Thu Mar 7 06:38:37 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=4b499d76-769a-40a0-93dc-4a31a59add28 / ext4 defaults 1 1
# 增加一个条件删除前方空格
[root@centos-7 ~]# sed -ri.bak '/^#/s/^#//;/^ /s/^ //' /root/fstab
[root@centos-7 ~]# cat fstab
/etc/fstab
Created by anaconda on Thu Mar 7 06:38:37 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=4b499d76-769a-40a0-93dc-4a31a59add28 / ext4 defaults 1 1
#删除#号行和空行
[root@centos-7 ~]# sed -i.bak '/^# */d;/^$/d' /root/fstab
[root@centos-7 ~]# cat fstab
UUID=4b499d76-769a-40a0-93dc-4a31a59add28 /
