shell script learning

--20180411--
$1:/dev/sdb

for i in $(ls /dev/escache*)
do
        find /sys/block/`echo $i|sed 's/\/dev\///g'`/slaves -name `echo $1|sed 's/\/dev\///g'`
        if [ $? -eq 0 ] ;then
                cache=$(ls /sys/block/`echo $i|sed 's/\/dev\///g'`/slaves |grep -v `echo $1|sed 's/\/dev\///g'`)
                /usr/sbin/bcache-super-show /dev/$cache | grep "cache device"
                if [ $? -eq 0 ] ;then
                        echo 1 > /sys/block/$cache/escache/set/stop
                fi
        fi
done

-- Test --

[' is actually a program, just like ls and other programs, so it must be surrounded by spaces: