当您正在学习如何充分使用linuxshell时，您可能会对如何操作字符串以获得最佳结果感到好奇。有鉴于此，今天的超级用户问答帖子回答了一位好奇读者的问题。

今天的问答环节是由SuperUser提供的，SuperUser是Stack Exchange的一个分支，是一个由社区驱动的问答网站分组。

问题

超级用户读者Nissim Kaufmann想知道Linux shell字符串中百分比符号的作用：

When using the Linux shell, what does the percent sign (%) do? For example:

Linux shell字符串中的百分比符号是做什么的？

答案

超级用户贡献者Marek Rost为我们提供了答案：

When the percent sign (%) is used in the pattern ${variable%substring}, it will return content of the variable with the shortest occurrence of substring deleted from the back of the variable.

This function supports wildcard patterns, that is why it accepts an asterisk (star) as a substitute for zero or more characters. It should be mentioned that this is Bash specific. Other Linux shells do not necessarily contain this function.

If you want to learn more about string manipulation in Bash, then I highly suggest reading the following page, Advanced Bash-Scripting Guide: Chapter 10. Manipulating Variables. Among many other handy functi***, it explains what a double percent sign (%%) does, for example.

I forgot to mention that when it is used in the pattern $((variable%number)) or $((variable1%$variable2)), the percent sign (%) character will function as a modulo operator.

When the percent sign (%) is used in different contexts, it should be recognized as a regular character only.

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