Question

I need to execute a command per line of some file. For example:

file1.txt 100 4
file2.txt 19 8

So my awk script need to execute something like

command $1 $2 $3

and save the output of command $1 $2 $3, so system() will not work and neither will getline. (I can’t pipe the output if I do something like this.)

The restriction to this problem is to use only awk. (i already had a solution with bashscriot + awk…but I only want awk…just to know more about this)

Answer 1

What’s wrong with using getline?

$ ./test.awk test.txt
# ls -F | grep test
test.awk*
test.txt

# cat test.txt | nl
     1  ls -F | grep test
     2  cat test.txt | nl
     3  cat test.awk

# cat test.awk
#!/usr/bin/awk -f
{
        cmd[NR] = $0
        while ($0 | getline line) output[NR] = output[NR] line RS
}
END {
        for (i in cmd) print "# " cmd[i] ORS output[i]
}