Manipulating column in a file in UNIX

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# 1  
Old 02-11-2014
Manipulating column in a file in UNIX


I have a file content.txt where I want to replace the value of second column of the file with half of the value of that column.
I only have to replace if the second column starts with COM_, rest all values have to be same

cat content.txt

Output file

Can you please let me know how to do it

Last edited by Scrutinizer; 02-11-2014 at 06:33 AM.. Reason: code tags
# 2  
Old 02-11-2014
awk '$2~/^COM_/{$3/=2}1' FS=\| OFS=\| file

# 3  
Old 02-11-2014
To get a little practice myself....

while read ColA ColB ColC ColD;do
    newB=$(echo "$ColB / 2" | bc)
    printf "$IFS$ColA$IFS$newB$IFS$ColC$IFS$ColD"

Hope this helps
# 4  
Old 02-11-2014
@sea: IFS can be used local to the read command:
while IFS=\| read ColA ColB ColC ColD
done < file

So IFS does not need to be set and reset..
Note that ColA is empty, ColD contains both columns 4 and 5 and ColC needs to be changed if ColB meets the criteria..

Last edited by Scrutinizer; 02-11-2014 at 07:17 AM..
This User Gave Thanks to Scrutinizer For This Post:
# 5  
Old 02-11-2014
 awk -F "|" '/COM_/{$3=$3 / 2;}1' OFS="|" filename

# 6  
Old 02-12-2014
Thanks Scrutinizer , the code worked well,

1 more question, is it possible to add one more level of validation,
like currently the code is working if the second column startes with _COM
I want to add one more level as the third column should only be "Scen"

Can you please let me know how can this be done
# 7  
Old 02-12-2014
Like so, you mean?
awk '$2~/^COM_/ && $4=="Scen" {$3/=2}1' FS=\| OFS=\| file

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