ls and help
mtchang@mtchang-mint~ $ ls --help
Usage: ls [OPTION]... [FILE]...
List information about the FILEs (the current directory by default).
Sort entries alphabetically if none of -cftuvSUX nor --sort is specified.
Mandatory arguments to long options are mandatory for short options too.
-a, --all do not ignore entries starting with .
-I, --ignore=PATTERN do not list implied entries matching shell PATTERN
mtchang@mtchang-mint ~ $ ls -l -a -h /etc/passwd /etc/shadow
-rw-r--r-- 1 root root 2.2K 9月 14 14:31 /etc/passwd
-rw-r----- 1 root shadow 1.6K 9月 14 14:31 /etc/shadow