understanding {%/*}/


 
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# 1  
Old 08-16-2010
understanding {%/*}/

Hi Gurus:
I am trying to understand the following line of code.I did enough of googling to understand but no luck.Please help me understand the follow chunk of code:

X=$0
MOD=${X%/*}/env.ksh

X is the current script from which I am trying to execute.

Say if X=test.ksh

$MOD is echoing : "test.ksh/env.ksh"

What I am trying to understand is,What exactly is {X%/*} doing.

Thanks in advance

Last edited by Scott; 08-16-2010 at 03:06 AM.. Reason: Moved from AIX forum
# 2  
Old 08-16-2010
Try running...

Code:
 >> ./test.ksh

You will find only ./env.ksh printed..{X%/*} seems to be chopping of a string that follows a '/' from $X.

if you run just 'test.ksh' you really dont have a '/' and hence you see test.ksh/env.ksh

Not sure why this was needed on your script...

Last edited by rajamadhavan; 08-16-2010 at 03:43 AM.. Reason: typo
# 3  
Old 08-16-2010
For example we run this
Code:
/home/ksh/test.ksh

X=$0
$0="/home/ksh/test.ksh"

X="/home/ksh/test.ksh"
MOD=${X%/*}/env.ksh

${X%/*} cut/delete from shortest `last slash and char group` from back of "/home/ksh/test.ksh"

that is "/test.ksh" so we cut "/test.ksh" string -->
% --> cut
/* --> slash and char group (string)
# 4  
Old 08-16-2010
Thanks Raja,ygemici.It really helped in understanding whats going on.
Raja,I am working on modifying a script.As part of it I am trying to understand the fucntionality of each function.
Code is trying to get an alternate configuration if specified from the command line ($1).If not use which is already existing using ($0).Below is the snippet:

Code:
 X=$0
   MOD="${X%/*}/env.ksh"
        
   if [ "$1" != "" ]; then
        MOD="${X%/*}/$1"
        if [ -f $MOD ]; then
           echo "Using override configuration file: [$MOD]"
        else
           echo "ERROR: Specified override configuration file [$MOD] was not found"
           MOD="${X%/*}/env.ksh"
           echo "Using default configuration file [$MOD]"
        fi
   fi

   cd `dirname $X`
   dir=`pwd`


   if [ -a $MOD ]; then
        echo "Common Environment Found.  Loading [$MOD]."
           SCRIPT_TYPE="WEB"
        . $MOD
        echo "Common Environment Load Complete."
   else
        echo "Common Environment NOT fond.  Aborting."
        exit -1
   fi

 
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