帮忙解释linux的一个脚本文件

#!/bin/shtest -f /usr/share/acpi-support/key-constants || exit 0. /etc/default/acpi-support
. /usr/share/acpi-support/power-funcsfor x in /tmp/.X11-unix/*; do
    displaynum=`echo $x | sed s#/tmp/.X11-unix/X##`
    getXuser;
    if [ x"$XAUTHORITY" != x"" ]; then
        export DISPLAY=":$displaynum"
. /usr/share/acpi-support/screenblank
    fi
done小弟刚接触linux   看不懂什么意思,各位高手帮帮忙把  最好每句代码都注释一下 ,在线等