bash正则expression式与报价？
下面的代码
number=1 if [[ $number =~ [0-9] ]] then echo matched fi 作品。 如果我尝试在正则expression式中使用引号，则会停止：
number=1 if [[ $number =~ "[0-9]" ]] then echo matched fi
我也尝试了"\[0-9\]" 。 我错过了什么？
有趣的是， bash先进的脚本指南build议这应该工作。
Bash版本3.2.39。
它在3.1和3.2之间改变了。 猜猜高级指南需要更新。
这是自bash-3.1发布以来添加到bash-3.2中的新特性的简要描述。 与往常一样，手册页（doc / bash.1）是查找完整描述的地方。
- Bash的新function
SNIP
F。 现在将string参数引用到[[command's =〜运算符]现在强制string匹配，与其他模式匹配运算符一样。
可悲的是，这将打破现有的报价使用脚本，除非你有洞察力存储模式的variables，并使用它们，而不是正则expression式直接。 下面的例子。
$ bash --version GNU bash, version 3.2.39(1)-release (i486-pc-linux-gnu) Copyright (C) 2007 Free Software Foundation, Inc. $ number=2 $ if [[ $number =~ "[0-9]" ]]; then echo match; fi $ if [[ $number =~ [0-9] ]]; then echo match; fi match $ re="[0-9]" $ if [[ $number =~ $re ]]; then echo MATCH; fi MATCH $ bash --version GNU bash, version 3.00.0(1)-release (i586-suse-linux) Copyright (C) 2004 Free Software Foundation, Inc. $ number=2 $ if [[ $number =~ "[0-9]" ]]; then echo match; fi match $ if [[ "$number" =~ [0-9] ]]; then echo match; fi match
Bash 3.2引入了兼容性选项compat31，它将bash正则expression式引用行为恢复为3.1
没有compat31：
$ shopt -u compat31 $ shopt compat31 compat31 off $ set -x $ if [[ "9" =~ "[0-9]" ]]; then echo match; else echo no match; fi + [[ 9 =~ \[0-9] ]] + echo no match no match
与compat31：
$ shopt -s compat31 + shopt -s compat31 $ if [[ "9" =~ "[0-9]" ]]; then echo match; else echo no match; fi + [[ 9 =~ [0-9] ]] + echo match match
链接到补丁： http : //ftp.gnu.org/gnu/bash/bash-3.2-patches/bash32-039
GNU bash，版本4.2.25（1）-release（x86_64-pc-linux-gnu）
string匹配和正则expression式匹配的一些例子
$ if [[ 234 =~ "[0-9]" ]]; then echo matches; fi # string match $ $ if [[ 234 =~ [0-9] ]]; then echo matches; fi # regex natch matches $ var="[0-9]" $ if [[ 234 =~ $var ]]; then echo matches; fi # regex match matches $ if [[ 234 =~ "$var" ]]; then echo matches; fi # string match after substituting $var as [0-9] $ if [[ 'rss$var919' =~ "$var" ]]; then echo matches; fi # string match after substituting $var as [0-9] $ if [[ 'rss$var919' =~ $var ]]; then echo matches; fi # regex match after substituting $var as [0-9] matches $ if [[ "rss\$var919" =~ "$var" ]]; then echo matches; fi # string match won't work $ if [[ "rss\\$var919" =~ "$var" ]]; then echo matches; fi # string match won't work $ if [[ "rss'$var'""919" =~ "$var" ]]; then echo matches; fi # $var is substituted on LHS & RHS and then string match happens matches $ if [[ 'rss$var919' =~ "\$var" ]]; then echo matches; fi # string match ! matches $ if [[ 'rss$var919' =~ "$var" ]]; then echo matches; fi # string match failed $ $ if [[ 'rss$var919' =~ '$var' ]]; then echo matches; fi # string match matches $ echo $var [0-9] $ $ if [[ abc123def =~ "[0-9]" ]]; then echo matches; fi $ if [[ abc123def =~ [0-9] ]]; then echo matches; fi matches $ if [[ 'rss$var919' =~ '$var' ]]; then echo matches; fi # string match due to single quotes on RHS $var matches $var matches $ if [[ 'rss$var919' =~ $var ]]; then echo matches; fi # Regex match matches $ if [[ 'rss$var' =~ $var ]]; then echo matches; fi # Above eg really is regex match and not string match $ $ if [[ 'rss$var919[0-9]' =~ "$var" ]]; then echo matches; fi # string match RHS substituted and then matched matches $ if [[ 'rss$var919' =~ "'$var'" ]]; then echo matches; fi # trying to string match '$var' fails $ if [[ '$var' =~ "'$var'" ]]; then echo matches; fi # string match still fails as single quotes are omitted on RHS $ if [[ \'$var\' =~ "'$var'" ]]; then echo matches; fi # this string match works as single quotes are included now on RHS matches
正如其他答案中所提到的，将正则expression式放在一个variables中是通过不同的bash版本实现兼容性的一般方法。 您也可以使用此解决方法来实现同样的事情，同时保持您的正则expression式在条件expression式中：
$ number=1 $ if [[ $number =~ $(echo "[0-9]") ]]; then echo matched; fi matched $
