逃避美元符号 [英] escaping the dollar sign

问题描述

我在my.cnf文件中有一行

  datadir = / var / lib / mysql 
 
 code> 

以下内容将按照预期将其更改为mysql3307。



  sed -i's / \ / var \ / lib \ / mysql $ / \ / var \ / lib \ / mysql3307 /'/etc/my.cnf 
  

但如果我有以下情况：



  datadir = / var / lib / mysql / 
  

然后下面的内容不会改变如预期的那样：



  sed -i's / \ / var \ / lib \ / mysql\ / $ / \ / var\ / lib\ / mysql3307 /'/etc/my.cnf 
  

我想更改mysql3307的路径，其中datadir是/ var / lib / mysql（带或不带/）



更新：



以下是问题：
上述命令都在一台服务器上运行，并且它们都不能在另一台服务器上运行。

预计，但我需要补充说明$以$ / $结尾的行

$ p $ sed -i's / \ / var\ / lib\ / mysql\ / / \ / var\ / lib\ / mysql3307 /'/etc/my.cnf


观察到：

Carot标志^按预期工作，但行尾符号$不符合。任何线索？

更新：

使用dos2unix命令后，它似乎正在工作。

解决方案

如果您的意图是仅更改具有该特定目录的路径，则需要更复杂一些。你必须在行尾没有尾随 / 的情况下捕捉它，并且你必须在它 结尾<$ c

但是你不想看到之类的东西， / var / lib / mysqlplus 因为这是一个完全不同的目录。

考虑使用扩展正则表达式，并使用一个不同的分隔符，所以你的命令看起来不像锯齿（ / \ / \ / \ / \ / \ / \ / \ / \ ）。通过这些修改以及对正则表达式本身的小修改，它可以正常工作：

  $ echo'
 / var / lib / mysqlplus 
 / var / lib / mysql / 
 / var / lib / mysql 
 / var / lib / mysql / xyz'| sed -E'| / var / lib / mysql（[$ /]）| / var / lib / mysql3307 \1 |'
 
 / var / lib / mysqlplus 
 / var / lib / mysql3307 / 
 / var / lib / mysql 
 / var / lib / mysql3307 / xyz 
  

I have a line in my.cnf file

datadir = /var/lib/mysql

The following changes it to mysql3307 as expected.

sed -i 's/\/var\/lib\/mysql$/\/var\/lib\/mysql3307/' /etc/my.cnf

But if I have the following:

datadir = /var/lib/mysql/

Then the following does not change the path as expected:

sed -i 's/\/var\/lib\/mysql\/$/\/var\/lib\/mysql3307/' /etc/my.cnf

I want to change the path to mysql3307 where datadir is /var/lib/mysql (with or without /)

Update:

Here is the issue: Both the above commands works on one server and none of them works on another.

The following works as expected, but I need to add that $ to indicate the lines ending with mysql/

sed -i 's/\/var\/lib\/mysql\//\/var\/lib\/mysql3307/' /etc/my.cnf

Observed:

The carot sign ^ works as expected, but end of line sign $ does not. Any clue?

Update:

It seems to be working after using "dos2unix" command.

解决方案

If your intent is to only change paths that have that specific directory, you need to be a bit trickier. You have to catch it at the end of a line without the trailing / and you also have to catch it everywhere it has the trailing / (end of line or not).

But you don't want to catch things like /var/lib/mysqlplus since that's a totally different directory.

Consider using extended regular expressions, and using a different separator character so you command doesn't look like sawteeth (/\/\/\/\/\/\/\/\). With those changes, and a small modification to the regular expression itself, it works fine:

$ echo '
/var/lib/mysqlplus
/var/lib/mysql/
/var/lib/mysql
/var/lib/mysql/xyz' | sed -E 's|/var/lib/mysql([$/])|/var/lib/mysql3307\1|'

/var/lib/mysqlplus
/var/lib/mysql3307/
/var/lib/mysql
/var/lib/mysql3307/xyz

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