Use awk results as parameters to another command

Question

I'm extracting rows from a set of text files with awk. The files look like this:

1000    1    75
1000    2    76
1001    1    76
1001    2    80

I'm searching several directories of these with this command:

awk -F"\t" '$3 == "76" { print $1"\t"$2}' ../benchmark/*/labels.txt

awk is giving me the correct output:

1000    2
1001    1

Now for each found row I must execute a script passing these two numbers as parameters, like this:

./build.oct 1000    2

What's the correct way to do that? I don't really care about script console output (it produces files).

Answer 1

You can also use xargs (-l makes it run a separate command for each line):

timp@helez:~/tmp$ awk -F"\t" '$3 == "76" { print $1"\t"$2}' test.txt | xargs -l ./build.oct 
$1 is  1000  and $2 is  2
$1 is  1001  and $2 is  1

timp@helez:~/tmp$ cat test.txt
1000    1   75
1000    2   76
1001    1   76
1001    2   80
timp@helez:~/tmp$ cat build.oct
echo '$1 is ' $1 ' and $2 is ' $2

As suggested in the comments you can also simplify the awk command, since both awk and xargs split on both tabs and spaces:

timp@helez:~/tmp$ awk '$3 == "76" {print $1,$2}' test.txt | xargs -l ./build.oct
$1 is  1000  and $2 is  2
$1 is  1001  and $2 is  1

Answer 2

This worked for me:

awk -F"\t" '$3 == "76" { printf "./build.oct %d %d\n", $1, $2}' \
../benchmark/*/labels.txt | bash

Answer 3

Consider this:

cat ../benchmark/*/labels.txt |
while IFS=$'\t' read P1 P2 P3 ; do
  [[ $P3 == 76 ]] && echo $P1 $P2
done |
sort -u |
parallel ./build.oct

• you save awk subprocess with readline built-in parser (see comments below)
• you avoid dupes with sort -u
• you leverage resource usage with parallel (or xargs -l1)

Other approach of interest, piloted by awk:

awk -F'\t' '$3==76 && !seen[$1,$2]++ {
  print $1 FS $2 | "parallel ./build.oct"
}' ../benchmark/*/labels.txt

• reuse input field separator FS instead of literal
• dupes are discarded using an array of counters
• you learn piping to awk subprocess

Answer 4

Assuming that columns 1 and 2 won't have whitespace in its entries, you can also do:

awk -F"\t" '$3 == "76" { print $1"\t"$2}' ../benchmark/*/labels.txt |
    while read a b; do ./build.oct $a $b; done

Answer 5

Using while is the best answer if you have multiple outputs:

I was able to delete many created WireGuard zones with UCI by the below command.

uci show firewall | grep wireguard | awk -F . '{printf "%s\n", $2}' | while read a ; do uci delete -q firewall."$a" ; done

Looping over found outputs and delete.

Edited

In your case all you have to do is:

awk -F"\t" '$3 == "76" { print $1"\t"$2}' ../benchmark/*/labels.txt | while read a b ; do ./build.oct "$a" "$b" ; done 

Answer 6

Gnu awk has a system function. You could run something along the lines of

awk '$3 == "76" { system("./build.oct " $1 " " $2) }' ....