[SOLVED] BASH: redirect stdin to variable number of subprocesses

BASH: redirect stdin to variable number of subprocesses

As the title says, I would like to redirect stdin to a variable number of output subprocesses.

If I had to redirect to output files I could do something like

files=(file_1 file_2 ... file_n)
tee ${files[*]} >/dev/null

but with subprocesses (using process substitutions, specifically), doing things like

programs=(">(exe_1 args_1)" ... ">(exe_n args_n)")
tee ${programs[@]} >/dev/null

will not intepret the >() as process substitutions but as literal filenames (for security reasons, I assume); also, the flags withing the substitutions are interpreted as flags of tee.

Is it possible to read ONE LINE from stdin and redirect it to all these processes (which, again, are variable in number: n is unknown)? Have I missed something, somewhere?

Thanks in advance and sorry for my bad English.

Solution

Instead of using process substitution, create a bunch of named pipes in a loop, and run each process with its stdin redirected to one of the pipes. Then use tee to write to all the pipes.

progs=(exe_1 exe_2 ...)
args=(args_1 args2 ...)
pipes=()
arraylenth=${#progs[@]}

for (( i=0; i<${arraylength}; i++ ))
do
    pipe=/tmp/pipe.$$.$i
    mkfifo "$pipe" && pipes+=("$pipe") && "$progs[i]" "$args[i]" < "$pipe" &
done

tee "${pipes[@]}" > /dev/null
# Clean up
rm -f "${pipes[@]}"

This solution has each program run with exactly 1 argument. It's hard to make it more general robustly because bash doesn't have 2-dimensional arrays.