preinst is in acpi-support 0.142.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 | #!/bin/sh
# Remove a no-longer used conffile (from http://wiki.debian.org/DpkgConffileHandling)
rm_conffile() {
    PKGNAME="$1"
    CONFFILE="$2"
    if [ -e "$CONFFILE" ]; then
        md5sum="`md5sum \"$CONFFILE\" | sed -e \"s/ .*//\"`"
        old_md5sum="`dpkg-query -W -f='${Conffiles}' $PKGNAME | sed -n -e \"\\\\'^ $CONFFILE[[:space:]]'{s/ obsolete$//;s/.* //p}\"`"
        if [ "$md5sum" != "$old_md5sum" ]; then
            echo "Obsolete conffile $CONFFILE has been modified by you."
            echo "Saving as $CONFFILE.dpkg-bak ..."
            mv -f "$CONFFILE" "$CONFFILE".dpkg-bak
        else
            echo "Removing obsolete conffile $CONFFILE ..."
            rm -f "$CONFFILE"
        fi
    fi
}
rm_confdir() {
    DIRNAME="$1"
    if [ -d "$DIRNAME" ]; then
        rmdir --ignore-fail-on-non-empty "$DIRNAME"
    fi
}
case "$1" in
install|upgrade)
    if dpkg --compare-versions "$2" lt-nl 0.141; then
        rm_conffile acpi-support /etc/acpi/events/asus-brightness-up
        rm_conffile acpi-support /etc/acpi/events/asus-brightness-down
        rm_conffile acpi-support /etc/acpi/asus-brn-down.sh
        rm_conffile acpi-support /etc/acpi/asus-brn-up.sh
    fi
    if dpkg --compare-versions "$2" lt-nl 0.142; then
        rm_conffile acpi-support /etc/acpi/asus-touchpad.sh
        rm_conffile acpi-support /etc/acpi/batterybtn.sh
        rm_conffile acpi-support /etc/acpi/ejectbtn.sh
        rm_conffile acpi-support /etc/acpi/events/ac
        rm_conffile acpi-support /etc/acpi/events/asus-f8sv-touchpad
        rm_conffile acpi-support /etc/acpi/events/asus-media-eject
        rm_conffile acpi-support /etc/acpi/events/asus-rotate
        rm_conffile acpi-support /etc/acpi/events/asus-touchpad
        rm_conffile acpi-support /etc/acpi/events/asus-video
        rm_conffile acpi-support /etc/acpi/events/battery
        rm_conffile acpi-support /etc/acpi/events/lenovo-touchpad
        rm_conffile acpi-support /etc/acpi/events/lenovo-touchpad2
        rm_conffile acpi-support /etc/acpi/events/lidbtn
        rm_conffile acpi-support /etc/acpi/events/panasonic-lockbtn
        rm_conffile acpi-support /etc/acpi/events/sleepbtn
        rm_conffile acpi-support /etc/acpi/events/tosh-battery
        rm_conffile acpi-support /etc/acpi/events/tosh-hibernate
        rm_conffile acpi-support /etc/acpi/events/tosh-ibutton
        rm_conffile acpi-support /etc/acpi/events/tosh-lock
        rm_conffile acpi-support /etc/acpi/events/tosh-mail
        rm_conffile acpi-support /etc/acpi/events/tosh-media
        rm_conffile acpi-support /etc/acpi/events/tosh-next
        rm_conffile acpi-support /etc/acpi/events/tosh-play
        rm_conffile acpi-support /etc/acpi/events/tosh-prev
        rm_conffile acpi-support /etc/acpi/events/tosh-stop
        rm_conffile acpi-support /etc/acpi/events/tosh-www
        rm_conffile acpi-support /etc/acpi/events/videobtn
        rm_conffile acpi-support /etc/acpi/hibernate.sh
        rm_conffile acpi-support /etc/acpi/lid.sh
        rm_conffile acpi-support /etc/acpi/lockbtn.sh
        rm_conffile acpi-support /etc/acpi/mailbtn.sh
        rm_conffile acpi-support /etc/acpi/mediabtn.sh
        rm_conffile acpi-support /etc/acpi/nextbtn.sh
        rm_conffile acpi-support /etc/acpi/playbtn.sh
        rm_conffile acpi-support /etc/acpi/power.sh
        rm_conffile acpi-support /etc/acpi/prevbtn.sh
        rm_conffile acpi-support /etc/acpi/rotatescreen.sh
        rm_conffile acpi-support /etc/acpi/screenblank.sh
        rm_conffile acpi-support /etc/acpi/sleepbtn.sh
        rm_conffile acpi-support /etc/acpi/sleep.sh
        rm_conffile acpi-support /etc/acpi/stopbtn.sh
        rm_conffile acpi-support /etc/acpi/thinkpad-stretchortouchpad.sh
        rm_conffile acpi-support /etc/acpi/videobtn.sh
        rm_conffile acpi-support /etc/acpi/webbtn.sh
        rm_conffile acpi-support /etc/init.d/acpi-support
    fi
esac
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