Check for empty string


 
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# 1  
Old 01-24-2008
Bug Check for empty string

Hello All,

I have written shell script whcih at the max 3 parameters.

When only one commandline argument and other two command line arguments are passed as empty string like

eg : archive ' ' ' '

Then i need to check whether the commandline arguments are empty or not.

i have use -n and ! -z but both of them fail for the above scenario.

Please let me know what is the alternative to solve this problem.

Thanks in anticipation
# 2  
Old 01-24-2008
Look for the number of command line parameters. If 1, then consider the other 2 empty.
# 3  
Old 01-24-2008
Quote:
Originally Posted by vino
Look for the number of command line parameters. If 1, then consider the other 2 empty.
Actually i need to check with one paramter and 3 paramters .

if it is one paramter then it is ok no need to check for empty strings.

But if it is 3 parameters then i need to check whether the other two are

emty since i know that there are 3 paramters.
# 4  
Old 01-24-2008
See this.

Code:
[/tmp]$ cat try.ksh
#! /bin/ksh


if [[ -n "$1" ]] ; then
    echo '$1'="[$1]"
else
    echo '$1' is empty
fi
if [[ -n "$2" ]] ; then
    echo '$2'="[$2]"
else
    echo '$2' is empty
fi
if [[ -n "$2" ]] ; then
    echo '$3'="[$3]"
else
    echo '$3' is empty
fi
[/tmp]$ ./try.ksh
$1 is empty
$2 is empty
$3 is empty
[/tmp]$ ./try.ksh 12 " " "  "
$1=[12]
$2=[ ]
$3=[  ]
[/tmp]$

This User Gave Thanks to vino For This Post:
# 5  
Old 01-24-2008
Quote:
Originally Posted by vino
See this.

Code:
[/tmp]$ cat try.ksh
#! /bin/ksh


if [[ -n "$1" ]] ; then
    echo '$1'="[$1]"
else
    echo '$1' is empty
fi
if [[ -n "$2" ]] ; then
    echo '$2'="[$2]"
else
    echo '$2' is empty
fi
if [[ -n "$2" ]] ; then
    echo '$3'="[$3]"
else
    echo '$3' is empty
fi
[/tmp]$ ./try.ksh
$1 is empty
$2 is empty
$3 is empty
[/tmp]$ ./try.ksh 12 " " "  "
$1=[12]
$2=[ ]
$3=[  ]
[/tmp]$


Hello vino,

thanks a lot for the quick reply.

The above code works if send the parameters as



sampleshellscript purge '' ''

i.e when i send null parameters.

but when i send parameters as

sampleshellscript purge ' ' ' ';

Then it does not work.

I wonder why ?that is why i was looking for an alternative to -n.
# 6  
Old 01-24-2008
Quote:
Originally Posted by rahman_riyaz
Hello vino,

thanks a lot for the quick reply.

The above code works if send the parameters as



sampleshellscript purge '' ''

i.e when i send null parameters.

but when i send parameters as

sampleshellscript purge ' ' ' ';

Then it does not work.

I wonder why ?that is why i was looking for an alternative to -n.
Do you mean like this ?

Code:
[/tmp]$ ./try.ksh 12 ' ' '  '
$1=[12]
$2=[ ]
$3=[  ]
[/tmp]$

# 7  
Old 01-24-2008
Quote:
Originally Posted by vino
Do you mean like this ?

Code:
[/tmp]$ ./try.ksh 12 ' ' '  '
$1=[12]
$2=[ ]
$3=[  ]
[/tmp]$

yeah exactly

when we give empty paramters as

sampleshellscript archive ' ' ' ' ;
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