To check host is alive.



check_exit_status ()
{
    local status="${exit_status:-$?}";
    local signal="";
    if [ ${status} -ne 0 ]; then
        if [ ${status} -gt 128 ]; then
            signal="$(builtin kill -l $[ status - 128 ] 2> /dev/null)";
            [ "${signal}" ] && signal=" ${signal}";
        fi;
        echo "[Exit ${status}${signal}]" 1>&2;
    fi;
    return 0
}

PROMPT_COMMAND=check_exit_status

============
#!/bin/bash

status=`/bin/ping -c 1 host_A | grep loss | awk '{printf("%s",$7)}'`

if [ $status = 0% ]; then

......

fi;