scope of arrays question

[awingnut]

I am having a problem with the scope of an array. I have a 'grep <blah blah> | while read line ; do' loop that builds and array and before the 'done' the array contains exactly what I want. After the 'done' the array is zeroed. I don't understand why the array does not survive the scope of this 'do'. In any case, how do I change the scope? TIA.

 

[LKBrwnDBA]

Linux? then this is how bash shell behaves.





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The person who says it can't be done should not interrupt the person doing it. -- Chinese proverb

 

[SamBones]

Does it work if you define and export the array variable before the loop?

 

[feherke]

Hi

This is a real PITA. I searched for workarounds and alternatives, for a long time but I found only one solution. Probably the ugliest possible :

i=0
eval `seq 5 7 | while read num; do echo arr[i++]=$num; done`
echo ${arr[*]}

Feherke.

http://rootshell.be/~feherke/

 

[awingnut]

Thanks. Export does not work either. Anyway I got the answer so I'll have to program around it.

 

[feherke]

Hi

Now I found out abit more. If you pipe something into [tt]while[/tt], then it will act as a new process and the values set inside will not be available after. But [tt]while[/tt] can get input through [tt]<[/tt] redirection, in which case everything set inside will remain available.

[gray]# no $val after this[/gray]
date [green]|[/green] [navy]while[/navy] read str; [navy]do[/navy] val=$str; [navy]done[/navy]
[gray]# $val will have the date after this[/gray]
date [green]>[/green] /tmp/temp; [navy]while[/navy] read str; [navy]do[/navy] val=$str; [navy]done[/navy] [green]<[/green] /tmp/temp

So you must use a temporary file, but I think sometime is not so big impediment.

Feherke.

http://rootshell.be/~feherke/