Differences between revisions 4 and 5
Revision 4 as of 2007-05-24 15:23:46
Size: 813
Editor: GreyCat
Comment: a workaround
Revision 5 as of 2007-05-24 15:48:37
Size: 1145
Editor: redondos
Comment: Added note about it working in some 3.2 versions.
Deletions are marked like this. Additions are marked like this.
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This one '''only works in bash 3.1''', not in bash 3.2 (and is untested in 3.0): This one '''only works in bash 3.1''' and '''some 3.2 revisions''' (it is untested in 3.0):
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The `=~` operator behavior changes drastically between 3.1 and 3.2, so be careful with it. The above expression is tested to work in bash ''3.1'' and ''3.2.{13,15,17}''; and it doesn't work in ''3.2.0''.
Please also note that the regexp does not need to be quoted in the 3.2 revisions where it works. --["redondos"]

Anchor(faq66)

I want to check if [[ $var == foo || $var == bar || $var == more ]] without repeating $var n times.

Here's a portable solution:

   case $var in
      foo|bar|more) ... ;;
   esac

And here's one that uses =~ (which requires bash 3.0 or higher):

   regex='^(foo|bar|more)$'
   if [[ $var =~ $regex ]]; then
      ...
   fi

This one only works in bash 3.1 and some 3.2 revisions (it is untested in 3.0):

   if [[ $var =~ '^(foo|bar|more)$' ]]; then
      ...
   fi

The =~ operator behavior changes drastically between 3.1 and 3.2, so be careful with it. The above expression is tested to work in bash 3.1 and 3.2.{13,15,17}; and it doesn't work in 3.2.0. Please also note that the regexp does not need to be quoted in the 3.2 revisions where it works. --["redondos"]

Normally I would never advocate sticking code into a variable and attempting to use it -- lots of people have enormous trouble because they try to do that. In the case of =~, though, it seems to be required. Personally, I'd just stick with the case. --GreyCat

BashFAQ/066 (last edited 2015-06-20 07:58:04 by ormaaj)