--help argument is a common choice for quickly learning about a command. Particularly useful,
--help shows the arguments for that particular command so we don’t have to look them up online.
Another option is the
whatis command, which prints a one-line description of the command.
Quickly Describe A Command
mkdir (1) - make directories mkdir (2) - create a directory
Note that in this case there are two mkdir commands with slightly different descriptions, but you can ignore that.
Get Help With A Command
In this example, we get help for the command
mkdir (make directory).
Usage: mkdir [OPTION]... DIRECTORY... Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit GNU coreutils online help: <http://www.gnu.org/software/coreutils/> Full documentation at: <http://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation'