Differences between revisions 9 and 11 (spanning 2 versions)
Revision 9 as of 2008-11-22 23:08:34
Size: 1367
Editor: GreyCat
Comment: first-line
Revision 11 as of 2012-04-29 23:44:04
Size: 487
Editor: ormaaj
Comment: rm old comments, rm regex examples because they're stupid and pointless, add category
Deletions are marked like this. Additions are marked like this.
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   case $var in    # Bourne
case "$var" in
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And here's one that uses `=~` (which requires bash 3.0 or higher): In Bash and ksh, [[glob|Extended globs]] can also do this within a `[[` command:
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   if [[ $var =~ $regex ]]; then
   # bash/ksh -- ksh does not need the shopt
   shopt -s extglob
   if [[ $var = @(foo|bar|more) ]]; then
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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

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 [[BashFAQ/050|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

The regexp works as long as it is quoted with bash version ''3.00.15(1)-release'' on CentOS4/RHEL4. I didn't bother checking whether bash is a patched version or not in CentOS4/RHEL4. --ellingsw

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

The portable solution uses case:

   # Bourne
   case "$var" in
      foo|bar|more) ... ;;

In Bash and ksh, Extended globs can also do this within a [[ command:

   # bash/ksh -- ksh does not need the shopt
   shopt -s extglob
   if [[ $var = @(foo|bar|more) ]]; then


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