regex match in Bash if statement doesn't work

Question

The below is a small part of a bigger script I\'m working on, but the below is giving me a lot of pain which causes a part of the bigger script to not function properly. The

Answer 1

There are two issues:

First, replace:

rh_reg="[rR]ed[:space:].*[Hh]at"

With:

rh_reg="[rR]ed[[:space:]]*[Hh]at"

A character class like [:space:] only works when it is in square brackets. Also, it appears that you wanted to match zero or more spaces and that is [[:space:]]* not [[:space:]].*. The latter would match a space followed by zero or more of anything at all.

Second, replace:

[ "$getos" =~ "$rh_reg" ]

With:

[[ "$getos" =~ $rh_reg ]]

Regex matches requires bash's extended test: [[...]]. The POSIX standard test, [...], does not have the feature. Also, in bash, regular expressions only work if they are unquoted.

Examples:

$ rh_reg='[rR]ed[[:space:]]*[Hh]at'
$ getos="red Hat"; [[ "$getos" =~ $rh_reg ]] && getos="redhat"; echo $getos
redhat
$ getos="RedHat"; [[ "$getos" =~ $rh_reg ]] && getos="redhat"; echo $getos
redhat