Currently the way /usr/sbin/alsa
in Debian knows the processes using the sound card looks like:
echo $( \
lsof +D /dev -F rt \
| awk '/^p/ {pid=$1} /^t/ {type=$1} /^r0x(74|e)..$/ && type == "tCHR" {print pid}' \
| cut -c 2- \
| uniq \
)
Which is rather ugly and depends on lsof
. I am looking for a POSIX solution without lsof
, perhaps using /proc.
time for i in /proc/*/fd/*; do readlink $i | grep -q /dev/snd/pcm && echo $i | awk -F '/' '{print $3}'; done | uniq
Unfortunately seems to take twice as long as the lsof
based snippet above. Can you make it faster, in order to make it a viable replacement?
Update I rewrote the above as:
#!/bin/sh
for i in /proc/[0-9]*/fd/*
do
if readlink $i | grep -q /dev/snd/pcm
then
IFS=/; set -- $i; unset IFS; echo $3
fi
done
But it seems to have the same performance as my earlier snippet. I suspect grep is the culprit.
Update: I have opened a Debian bug on the topic.