Shell Programming and Scripting

#!/usr/bin/env ksh

last $1 | awk -v month="$(date +%b)" '
   /wtmp/  ||  /still logged in/ || / sshd / { next; }

      NF > 0  &&  $(NF-5) == month {
        gsub( "\\(", "", $NF );         # ditch parens
        gsub( "\\)", "", $NF );

        if( index( $(NF), "+" ) )       # days+hr:min
        {
            split( $NF, b, "+" );       # capture days, leave hr and min in a
            days += b[1];
            split( b[2], a, ":" );
        }
        else
            split( $NF, a, ":" );       # no days, just caputre hr and min

        hr += a[1];
        min += a[2];
    }

    END {
        eh = int( min/60 );     # extra hours
        hr += eh;
        min -= 60 * eh;

        ed = int( hr/24 );      # extra days
        days += ed;
        hr -= 24 * ed;
        printf( " %dd%dh%dm\n", days, hr, min );   # print in XdXmXh notation
    }
'
exit $?