sed 找出含有某个字符串的行注释掉

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1、源文件例子

[root@node1 ~]# cat /etc/fstab#
# /etc/fstab
# Created by anaconda on Mon Mar 1 18:32:15 2021
#
# 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
#
/dev/mapper/centos-root / xfs defaults 0 0
UUID=3fa2b010-61bc-480e-bd49-cb7bee120fe3 /boot xfs defaults 0 0
/dev/mapper/centos-swap swap swap defaults 0 0
[root@node1 ~]#

2、cp一个文件出来测试修改 fs.txt

sed -i '/swap/s/^/#/g' fs.txt

3、diff看一下 ok了

[root@node1 ~]# diff fs.txt /etc/fstab
11c11
< #/dev/mapper/centos-swap swap swap defaults 0 0
---
> /dev/mapper/centos-swap swap swap defaults 0 0
[root@node1 ~]# cat /etc/fstab

4、如果要幂等执行得判断是否被注释过了如果注释过了则不执行不然就执行然后再判断这个适合用 until 命令

until grep swap fs.txt |grep "#" >/dev/null;do echo "disable swap" && sed -i '/swap/s/^/#/g' fs.txt;done

5、测试OK 换成实际环境就是下面的可以重复执行

until grep swap /etc/fstab |grep "#" >/dev/null;do echo "disable swap" && sed -i '/swap/s/^/#/g' /etc/fstab;done