On the command line
There is an almost universal convention on UNIX systems that issuing a command followed by –help will bring up a summary of the key information needed to use a particular command. Sometimes this is just a few lines:
And sometimes a few pages:
The core UNIX commands will adhere to this standard, but not all developers of other applications adhere to this standard. If the –help command doesn’t bring up any usage information try using the h or -? flags as alternatives. If all else fails, just issuing the command on it’s own often brings up some usage information.
Most commands also have a larger body of text that is installed into the operating systems manual database. This can be accessed using the man command. E.g.:
You can scroll though this information using the up and down arrows, use spacebar to advance page by page and press q to exit.