有时候看到某个shm有好几个进程attach了，但是具体是哪些进程呢？ 网上查了一下，http://stackoverflow.com/questions/5658568/how-to-list-processes-attached-to-a-shared-memory-segment-in-linux 方法是grep $shmid /proc/*/maps 可以找出attach的进程。

get_attach_pid.sh

#!/bin/bash

if [ $# -lt 1 ]; then
	echo "usage: " $0 " shmid ..."
    exit 0
fi

tmpfile=/tmp/shm$$

for x ; do
	grep $x /proc/*/maps > $tmpfile 2>/dev/null
	echo ==== $x ====
	pids=$(awk -F/ '{print $3}' $tmpfile)
	for pid in $pids; do
		echo $pid $(cat /proc/$pid/cmdline | tr '\000' ' ')
	done
done

rm $tmpfile