On Apr 9, 2011, at 6:31 AM, Dino Vliet <[email protected]> wrote:
> Hi folks,
> I'm having trouble with a little shell script. Can somebody explain me why I
> get 3 times "expr: syntax error" in my console after I run this little
> script?
>
> #! /usr/local/bin/bash
> # testscript
>
> var1="trees.J48" #other value will be rules.Jrip, rules.DecisionTable
> len=${#var1}
> ind=`expr index $var1 s`
> pos=`expr $len - $ind`
> out=`expr substr $var1 $ind $pos`
>
> I would expect (and want the following to happen):
>
> $ind should contain 6
> $pos should contain 3
> $out should contain J48 (other values will have to be Jrip,DecisionTable)
>
> Can anyone help me with this?
This would be a /bin/sh compatible (read: portable) way to accomplish the above:
#!/bin/sh
# testscript
var1="trees.J48" #other value will be rules.Jrip, rules.DecisionTable
len=${#var1}
ind=`echo "$var1" | awk '{print index($0,"s")+1}'`
pos=$(( $len - $ind ))
out=`echo "$var1" | awk -vind="$ind" -vpos="$pos" '{print
substr($0,ind+1,pos)}'`
Though, there are certainly easier ways to get at what it is that I assume your
after:
#!/bin/sh
# testscript
var1="trees.J48" #other value will be rules.Jrip, rules.DecisionTable
out="${var1##*.}"
--
Devin
>
> Thanks
>
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