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#1 (permalink)

04-04-2009

hcclnoodles hcclnoodles is offline

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Join Date: Mar 2002

Posts: 272

quck question about expr and (( ))

Hi

just a quick question, i have always used

Code:

var=`expr $var + 1`

to increment a variable or to perform arrithmetic. however, i found another script which did this

Code:

(( var = var + 1 ))

which worked exactly the same ? ... can anybody tell me where I can read up on this, and where I can find docs ? i tried googling and i dont even know where to start ...what is this method called ?

likewise.. whats the deal with using double square brackets on the ' test' command .. ie

Code:

   if [[ $account = "*hello*" ]] ; then

i looked at the man page for test but couldnt find anything about the use of double brackets ?

Can anybody help me grasp these two double bracket methods or point me to some docs where i can read about where and how to use them ?

Any help would be great

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