[root@node29 ~]# vim ./test.sh 
my_tip()
{
    echo "${FUNCNAME[1]}(), line ${BASH_LINENO[0]}: $*"
}

show_file_list()
{
    echo "begin"
    file_list=`ls ./big_files 2> /dev/null`
    if [ "$?" != 0 ]; then
        my_tip "Invalid file list!"
        return 1
    fi
    echo "file_list is: ${file_list}"
}

show_file_list