linux - How to use STDIN twice from pipe

Question

I have a awk script something like

awk 'FNR==NR {col1[$1]++; col2[$2]++; next} {print $0, col2[$2] "/" length(col1)}' input input

But in case I have lot of files and need to use this script for concatenated files together like:

cat *all_input | awk 'FNR==NR {col1[$1]++; col2[$2]++; next} {print $0, col2[$2] "/" length(col1)}' STDIN STDIN

Does not work. How to use STDIN twice from pipe?

Answer 1

You don't need to use a pipe. If you are using bash use process-substitution as <(cmd) i.e. to achieve a redirection where the input or output of a process (some sequence of commands) appear as a temporary file.

awk 'FNR==NR {col1[$1]++; col2[$2]++; next} {print $0, col2[$2] "/" length(col1)}' <(cut -f3 5- input) <(cut -f3 5- input)