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Shell Programming and Scripting

Read Line is not Updated

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# 1  
Old 09-18-2013
Read Line is not Updated
Hi,

Is there a way to reflect the recent changes in the file being read when using "while read line" loop? Thanks!

script:
Code:
while read line
do
    echo $line
    cat x.dat|sed 's/2/6/g' > x.dat.temp
    mv x.dat.temp x.dat
done < x.dat

The results is still getting below, even though the 2 had been updated already to 6.
Code:
1
2
3
4
5

Thanks
Last edited by Scrutinizer; 09-18-2013 at 02:59 AM.. Reason: code tags
# 2  
Old 09-18-2013
Hi, this script does not make sense. The while read loop is reading from the same file that is being modified within the loop itself. You cannot do that. What would you like to accomplish?
# 3  
Old 09-18-2013
You don't even need a while loop if you want to simply replace 2 with 6.

sed alone will suffice:
Code:
sed 's/2/6/g' x.dat > x.dat.temp; mv x.dat.temp x.dat

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