bash 如何检查字符串是否仅包含 AZ、az 和 0-9？
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How to check if a string only contains A-Z, a-z and 0-9?
提问by kheraud
What is the best way to validate a string with a pattern? I would use PCRE but I don't know if it is embedded in each shell and how to use it.
使用模式验证字符串的最佳方法是什么？我会使用 PCRE，但我不知道它是否嵌入在每个 shell 中以及如何使用它。
For example, how could I validate that variable only contains A-Z, a-Z and 0-9 and does not contain spaces, ', ", ... ?
例如，我如何验证该变量仅包含 AZ、aZ 和 0-9，并且不包含空格、'、"、...？
回答by Ignacio Vazquez-Abrams
$ [[ "foo" =~ ^[A-Za-z0-9]*$ ]] ; echo $?
0
$ [[ "foo " =~ ^[A-Za-z0-9]*$ ]] ; echo $?
1
回答by Martin
if [[ "$VARIABLE" =~ ^[[:alnum:]]*$ ]]; then do something; fi;
useful resources: http://bashshell.net/regular-expressions/, http://www.gnu.org/software/bash/manual/bashref.html
有用的资源：http://bashshell.net/regular-expressions/，http://www.gnu.org/software/bash/manual/bashref.html
回答by Seth Robertson
if `echo $VARIABLE | egrep '[^A-Za-z0-9]'`; then echo VARIABLE IS BAD; fi
A pure shell option
纯 shell 选项
case "$VARAIBLE" in *[^A-Za-z0-9]*) echo VARIABLE IS BAD;; esac
回答by Jo So
The one and only portable (no bash crap) way:
唯一的便携（没有 bash 废话）方式：
`[ "${var%%*[^A-Za-z0-9]*}" ]`
Note that no external program is started, so this is more performant than grepet al. solutions.
请注意，没有启动任何外部程序，因此这比grep等人的性能更高。解决方案。
Note that character classes are generally (not only in shell) locale-sensitive.
请注意，字符类通常（不仅在 shell 中）对区域设置敏感。
var=?
[ "${var%%*[^a-z]*}" ] && echo match # prints "match"
So you might want to consider temporarily setting the locale to Cor make the class yourself
因此，您可能需要考虑暂时将语言环境设置为C或自己创建类
`[ "${var%%*[^abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789]*}" ]`
