【04-04】刪除/etc/fstab檔案中所有以#開頭，後面至少跟一個空白字元的行的行首的#和空白字元

# 備份檔案到root家目錄做測試
[root@centos-7 ~]# cp /etc/fstab /root/fstab
#檢視該檔案
[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

#對檔案進行處理 /^# 取得各行已#開頭的行後傳遞給 s進行替換 s/^#// 替換為空後進行對檔案修改
[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

# 增加一個條件刪除前方空格
[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
#刪除#號行和空行
[root@centos-7 ~]# sed -i.bak '/^# */d;/^$/d' /root/fstab
[root@centos-7 ~]# cat fstab
UUID=4b499d76-769a-40a0-93dc-4a31a59add28 /