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Shell Programming and Scripting

using variables in case statement

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# 1  
Old 10-28-2009
using variables in case statement
is it possible to call a variable in a case statement, for example
Code:
lsmonth=Jan|Feb
l |while read ans
do
   mymonth=`echo $ans |awk '{print $6}'`
   case $mymonth in
    $lsmonth) echo do something
    ;;
    *) echo do something else
    ;;
  esac
done

I want to use $lsmonth after the case $mymonth in
# 2  
Old 10-28-2009
Code:
lsmonth='Jan|Feb'
while read ans
do
	cmd=$(
		echo "
		case $ans in
		$lsmonth) echo do something
		;;
		*) echo do something else
		;;
		esac
		" )
eval $cmd
done

Please use code tags.
# 3  
Old 10-28-2009
Quote:
Originally Posted by jim mcnamara
Code:
lsmonth='Jan|Feb'
while read ans
do
	cmd=$(
		echo "
		case $ans in
		$lsmonth) echo do something
		;;
		*) echo do something else
		;;
		esac
		" )
eval $cmd
done


That will not work in most shells. The variable will be considered a single string, not as two choices.

And there's no need for command substitution:

Code:
case $ans in
     a|b) cmd='echo "do something"' ;;
     *) cmd='echo "do something else"' ;;
esac
eval "$cmd"

# 4  
Old 10-28-2009
Quote:
Originally Posted by cfajohnson

That will not work in most shells. The variable will be considered a single string, not as two choices.

And there's no need for command substitution:

Code:
case $ans in
     a|b) cmd='echo "do something"' ;;
     *) cmd='echo "do something else"' ;;
esac
eval "$cmd"

but doesn't that defeat the purpose of using a variable as valid 'choice'?
Is there a way to do it the way the OPed wanted originally?
I remember seeing something very similar done somewhere...
# 5  
Old 10-28-2009
Quote:
Originally Posted by vgersh99
but doesn't that defeat the purpose of using a variable as valid 'choice'?

There is no purpose in using syntax that is not supported.
Quote:
Is there a way to do it the way the OPed wanted originally?
I remember seeing something very similar done somewhere...

Code:
eval "case \$ans in $lsmonth) .... esac"

# 6  
Old 10-28-2009
Quote:
Originally Posted by cfajohnson
Code:
eval "case \$ans in $lsmonth) .... esac"

thanks - appreciated.
# 7  
Old 10-28-2009
Code:
lsmonth1=Jan; lsmonth2=Feb
l |while read ans
do
   mymonth=`echo $ans |awk '{print $6}'`
   case $mymonth in
    $lsmonth1|$lsmonth2) echo do something
    ;;
    *) echo do something else
    ;;
  esac
done
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