# your script as you have it up to here....
# cleanup before exit
#rm $big_file

grep $user  /tmp/tst/$USER.wtmp | awk '
    /wtmp begins/ { next; }
    /still logged in/ { next; }
    $0 == reboot { next; }

    NF > 0  {
        if( NR > 1 )
            printf( "\n" );

        printf( "       User:\t%s\n", $1 );     # user
        printf( "      Start:\t%s %s %s %s\n", $3, $4, $5, $6 );
        if( $9 == "down" )
            printf( "        End:\tshutdown\n" );
        else
            printf( "        End:\t%s %s %s %s\n", $9, $10, $11, $12 );

        if( substr( $NF, 1, 1 ) == "(" )
        {
            t = $NF;
            h = "localhost";
        }
        else
        {
            t = $(NF-1);
            h = $NF;
        }

        gsub( "[()]", "", t );
        printf( "    Time On:\t%s\n", t );
        printf( "Remote Host:\t%s\n", h );
} '