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problem with redirect stdout to file

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# 1  
Old 12-06-2006
Data problem with redirect stdout to file
Hi all hope you can help as I am going MAD!!! Smilie

The below is in a shell script but the redirection in the sed line does not work and outputs to the screen and the $fname_2 does note get created ?????

Can any one help ??

Code:
#!/bin/ksh
cd /app/
for fname in `ls -1 X*`
do
sed 1d $fname > $fname_2
done

if I run
Code:
sed 1d filename > filename_2

on the command line it works ???
# 2  
Old 12-06-2006
We ran into the same problem the other day in one of our scripts.

You need to change your $fname to ${fname}

Look at this script to see the behaviour.

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

a=12
b=34
echo $a_$b
echo ${a}_$b
[/tmp]$ sh try.sh
34
12_34
[tmp]$

From man sh

Code:
       ${parameter}
              The value of parameter is substituted.  The braces  are  required
              when  parameter  is  a  positional  parameter  with more than one
              digit, or when parameter is followed by a character which is  not
              to be interpreted as part of its name.

Last edited by vino; 12-06-2006 at 07:32 AM..
# 3  
Old 12-06-2006
Quote:
Originally Posted by vino
We ran into the same problem the other day in one of our scripts.

You need to change your $fname to ${fname}

Look at this script to see the behaviour.

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

a=12
b=34
echo $a_$b
echo ${a}_$b
[/tmp]$ sh try.sh
34
12_34
[tmp]$

Hi thanks that did the trick.

Do you know why this is the case ?? I have used the $fname in loads of scripts before with out having to use the {}
# 4  
Old 12-06-2006
Yes.
$fname_2 expects that fname_2 is the name of the variable - and you want the _2 to be part of the name not part of a new variable name.

You can also use $fname"_2" to force the _2 to be a constant, and not a variable.
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