Finding processes using ALSA sound fast

There is an answer for this question on the ALSA FAQ. On my system, using fuser is way faster than using lsof.

fuser -v /dev/snd/*

You start a lot of processes here. Instead you can try doing in a similar way to the lsof script you posted... but replacing lsof by a shell for loop:

If you want to avoid launching lots of grep processes, start only one:

#!/bin/shfor i in /proc/[0-9]*/fd/*do    echo ${i%/fd/*} $(readlink $i)done | grep -q /dev/snd/pcm

This takes now 4.5s on my desktop, compared to 7.5s when there's one grep process for each opened file.

But... your grep is not necessary here, I think. If you care so much, you can try:

#!/bin/shfor i in /proc/[0-9]*/fd/*do    var="$(readlink $i)"    if test x"$var" != x"${var#/dev/snd/pcm}"    then        echo $i    fidone

This is even faster for me (test is almost always a shell builtin), but I guess this is more because of bad testing methods. Try yourself.

You don't say what kind of timescales you're looking for but for your alternative suggestion

for i in /proc/[0-9]*/fd/*;

might work and give you a bit of speed up, as might using cut rather than awk.