help is a program that takes a linux program as an input and prints a helpful message about the input program’s behavior, its optional/required flags, and how to successfully use the program.
$ help echo <info about echo> $ help cd <info about cd>
Useful Options / Examples
$ help -d echo echo - Write arguments to the standard output. $ help -d cd cd - Change the shell working directory.
Including the -d flag makes the help program print a short description of the input program.
$ help -s echo echo: echo [-neE] [arg ...] $ help -s cd cd: cd [-L|[-P [-e]] [-@]] [dir]
Including the -s flag makes the help program print a short description of the input program’s usage.