How to execute a command for each loop in awk?

Question

I'm using awk to split a binary stream and I can get each part into a for loop like this.

for(i=1;i<=NF;i++)

I don't want to convert each field to text or arguments, but simply pass it directly to a command.

I'm trying to find something like this,

for(i=1;i<=NF;i++) system("decode")

but this obviously doesn't work. decode receives no input.

How do I get decode to receive each field in the loop?

Answer 1

Doesn't this works for you?

for(i=1;i<=NF;i++) print $i | "decode"
close("decode")

It sends each field (or byte in your case) to a pipe connected to the "decode" program.

After that, close the "decode" pipe to force a flush of all the data on that pipe.

You can read more about gawk redirection on https://www.gnu.org/software/gawk/manual/html_node/Redirection.html

If you want to execute "decode" for each single byte, just close the pipe in each iteration:

for(i=1;i<=NF;i++) {
    print $i | "decode"
    close("decode")
}

Answer 2

Is this what you are trying to do?

awk '{for(i=1; i<=NF; i++) system("decode "$i)}' input_file.txt

This should pass each field, contained in awk variable $i, to the decode external program. Mind the variable is outside the quotes for "decode ", or it would be interpreted by the shell instead of awk.