#!/bin/sh
#
# shm_clear: clean out unattached (NATTACH=0) shm segments.
# See ipcs(1) and ipcrm(1).  Tested on Linux and Solaris.
#
# Usage:
#    shm_clear      list and prompt for removal of your unattached shm segments.
#    shm_clear -y   assume "yes" to all the removal prompts.
#    shm_clear -l   only list (all of) your shm segments and exit.
#

#set -xv
if echo "$1" | grep '^-h' > /dev/null; then
    # -h or -help 
    tail +3 $0 | head -9
    exit
fi

if [ "X$USER" = "X" ]; then
    USER=$LOGNAME
fi
l_arg="shmid.*owner|CREATOR|$USER"

# set up OS dependent cmdline opts, etc.
if [ `uname` = "Linux" ]; then
    m_arg="-m"
    r_arg="shm"
    g_arg="^0x"
    s_cmd="ipcs $m_arg -i %ID"
    awkcut='{print $2, $6}'
elif [ `uname` = "SunOS" ]; then
    m_arg="-ma"
    r_arg="-m"
    g_arg="^m"
    s_cmd="ipcs $m_arg | egrep '  %ID  |CREATOR' | grep -v IPC.status"
    awkcut='{print $2, $9}'
else
    echo unsupported OS: `uname`
    exit 1
fi

list() {
    if [ "X$1" = "X-L" ]; then
        l_arg="$l_arg|."
        echo "All shm segments for all:"
    else
        echo "All shm segments for $USER:"
    fi
    ipcs $m_arg | egrep "$l_arg"
    echo
}

show() {
    cmd=`echo "$s_cmd" | sed -e "s/%ID/$1/g"`
    eval $cmd
}

remove() {
    echo ipcrm $r_arg $1
         ipcrm $r_arg $1
}

if [ "X$1" = "X-l" -o "X$1" = "X-L" ]; then
    # list only.  both attached and unattached listed.
    list $1
    exit 0
fi

if [ "X$1" = "X-y" ]; then
    shift
    yes=1   # assume "yes" to all delete questions.
else
    yes=""
fi

list

ids=`ipcs $m_arg | grep "$g_arg" | grep $USER | awk "$awkcut" | grep ' 0$' | awk '{print $1}'`
if [ "X$ids" = "X" ]; then
    echo "No unattached shmids for $USER."
fi

for id in $ids 
do
    if [ $yes ]; then
        :
    else
        echo "-------------------------------------"
        show $id
        printf "\nDelete? [y]/n "
        read x
        if echo "$x" | grep -i n > /dev/null; then
            continue
        fi
    fi
    remove $id
done

