Getting the help for commands on Linux

Most GNU utilities have a ––help option that displays information about the utility.

 

$ cat --help

Usage: cat [OPTION] [FILE]...
Concatenate FILE(s), or standard input, to standard output.
  -A, --show-all           equivalent to -vET
  -b, --number-nonblank    number nonblank output lines
  -e                       equivalent to -vE
  -E, --show-ends          display $ at end of each line

...

If the information that ––help displays runs off the screen, send the output through the less pager (page 31) using a pipe:

$ ls --help | less