Essential Bash builtin commands

The first category of essential commands that we'll examine are builtins: they are included as part of the bash program. In fact, the very first command we'll look at, called type, is itself designed to help you tell what any kind of command is.

For all of these commands, Bash can provide help on usage with the help program. For example, to get help on the type command, you would type:

bash$ help type

The type command

The type command, given the name of any command or commands, gives you information about what kind of command it is:

bash$ type echo
echo is a shell builtin
bash$ type grep
grep is /bin/grep

It identifies shell keyword, too:

bash$ type for
for is a shell keyword

We can...