using awk command in for/while loop

Question

This is the content of my input file(rpm.txt).

U25,1007
U27,1269

I would like my code to use this file (rpm.txt) as input, change directory to U25, and search for 1007 in U25/test.csv, and print all columns in test.csv that match 1007; and repeat for every line.

This is the code for this, without the loop:

cat U25/test.csv | awk -F ',' '$1 == 1007 {print $0}' > x
cat U27/test.csv | awk -F ',' '$1 == 1269 {print $0}' >> x

Would anyone be able to help me write this as a loop?

By the way, you can safely omit {print $0} as that is what awk does by default anyway. — Mark Setchell
– Mark Setchell, Commented Jun 3, 2017 at 10:40
Why? Why not just have awk read rpm.txt and then search for 1007 in U25/test.csv, etc. in one invocation of the tool? No cd-ing or shell loops required. — Ed Morton
– Ed Morton, Commented Jun 3, 2017 at 14:08
That's a great idea! Would you be able to help me translate that to a command? I know it would probably use awk -v, but not sure of the final command. — aram
– aram, Commented Jun 3, 2017 at 18:07

Nahuel Fouilleul · Accepted Answer · 2017-06-03 05:03:52Z

2

What about

while IFS=, read dir num; do
    awk -v num="$num" ... '$1 == num ... '  <"$dir"/test.csv
done <rpm.txt >x

answered Jun 3, 2017 at 5:03

Nahuel Fouilleul

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1 Comment

aram Over a year ago

I am not able to get this to work, what am I required to put in the . . . in your command?

perreal · Accepted Answer · 2017-06-03 05:08:42Z

0

Some stupid way of doing this without any loops, by creating commands like grep "^1007," U25/test.csv and feeding them to shell:

sed 's!\(.*\),\(.*\)!grep "^\2," \1/test.csv!' input | sh

answered Jun 3, 2017 at 5:08

perreal

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1 Comment

aram Over a year ago

This works for me! Would you be able to explain your command a little more to me? Particularly !(.*),(.*)!

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