使用 sed 更改/etc/fstab [英] Using sed to change /etc/fstab

问题描述

我想在脚本中更改 /etc/fstab.我想将 acl 属性添加到根分区.

I would like to change /etc/fstab inside a script. I want to add the aclattribute to the root partition.

一个 fstab 行条目如下所示:

One fstabline entry looks like this:

UUID=730aee20-52b7-4920-75cd-d0d995ef2445 /   ext3   errors=remount-ro 0   1

我想把它改成:

UUID=730aee20-52b7-4920-75cd-d0d995ef2445 /   ext3    acl,errors=remount-ro 0   1

我想:1.搜索根分区/的行2.在/

I thought: 1. Search line with root partition / 2. insert acl after /

我怎样才能用 sed 做到这一点?

How can I do that with sed?

推荐答案

当我们都拥有 awk 时，谁还需要一些 3rd 方工具?

Who needs some 3rd party tool when we all have awk?

awk '$2~"^/$"{$4="acl,"$4}1' OFS="\t" /etc/fstab

示例输出

$ awk '$2~"^/$"{$4="acl,"$4}1' OFS="\t" /etc/fstab
/dev/sda2        swap             swap        defaults         0   0
/dev/sda5       /       ext4    acl,defaults    1       1
/dev/sda1        /boot            ext4        defaults         1   2
/dev/sda6        /home            ext4        defaults         1   2
/dev/sdb1        /backup          ext4        defaults         1   2
#/dev/cdrom      /mnt/cdrom       auto        noauto,owner,ro  0   0
/dev/fd0         /mnt/floppy      auto        noauto,owner     0   0
devpts           /dev/pts         devpts      gid=5,mode=620   0   0
proc             /proc            proc        defaults         0   0
tmpfs            /dev/shm         tmpfs       defaults         0   0

说明

1. $2~"^/$" 搜索第二个字段 $2 看它是否与正斜杠本身匹配 ^/$
2. {$4="acl,"$4} 如果我们看到匹配，将 acl 添加到第 4 个字段的开头 $4
3. }1 这是一个 awk 快捷方式，相当于 print $0，即打印整行(包括我们可能有的任何更改)制作)
4. OFS="\t" 将输出字段分隔符 OFS 设置为选项卡 \t.默认为空格
5. /etc/fstab 我们要用作输入的文件

1. $2~"^/$" Search the 2nd field $2 to see if it matches a forward slash by itself ^/$
2. {$4="acl,"$4} If we see a match, prepend acl to the beginning of the 4th field $4
3. }1 This is an awk shortcut which is equivalent to print $0, i.e. print the whole line (including any alterations we may have made)
4. OFS="\t" Set the Output Field Separator OFS to a tab \t. The default is space
5. /etc/fstab The file we want to use as input

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