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Shell Programming and Scripting

Variables scope.

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# 8  
Old 05-23-2008
So is there a way it can be done in sh shell.
# 9  
Old 05-24-2008
The idea is not to spawn a sub-shell:

Code:
$ cat fcheck
#!/bin/sh

FLAG=0;
while read data
do
        echo "data=$data"
        FLAG=1;
done < filename

echo $FLAG
$ ./fcheck
data=line1
data=line2
1

This was already suggested by abhisek.says and contrary to what you reported, it evidently DOES work in Bourne shell.

HTH
# 10  
Old 08-19-2008
I just tested it under a Solaris machine and it does NOT work.

Script:
Code:
#!/bin/sh

FLAG=0;
while read data
do
        echo "data=$data"
        FLAG=1;
done < filename

echo $FLAG

Output:
Code:
./fcheck
data=line1
data=line2

# 11  
Old 08-19-2008
Data
You are right - I must have some mistake. It does NOT work in Bourne shell. Infact I could only make it work in ksh.
# 12  
Old 08-19-2008
another way to do that in bash is :
Code:
#!/bin/sh
FLAG=0
exec 4<&0
exec <$1
while read line
do
    FLAG=1
done
echo $FLAG
exec 0<&4 4<&-

$1=the file u want to read
# 13  
Old 08-19-2008
Setting FLAG within a while loop works in bash, ksh, ash, zsh. It does not work in sh (Bourne shell) because redirection causes a subshell. From the sh(1) manpage on Solaris.
Quote:
If the input or the output of a while or until loop is
redirected, the commands in the loop are run in a sub-shell,
and variables set or changed there have no effect on the
parent process:

lastline=
while read line
do

lastline=$line
done < /etc/passwd
echo "lastline=$lastline" # lastline is empty!
# 14  
Old 09-10-2008
Today i needed a new script which reads line for line and i tried a for loop.
So I made the following script:
Code:
bla=2
echo $bla
for i in `cat ./config.txt`
do
  echo $i
  bla=5
done

echo $bla

First $bla =2 and by the second print $bla=5.
Tested under bourne shell on Solaris and Suse.
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