Tab-completion (saves typing by deterministically completing a command for you)
One extremely time-saving feature built into the Bash Shell
is the ability to "tab-complete" commands. Simply hit the tab key while
you are typing a command, and the shell will automatically finish the command
for you. Or, if it is ambiguous, it will provide options (you might have to
type tab again). For example, if you want to type the history command,
you can type his-tab and the rest of the command will be filled in:
$ his (then hit tab, at which point the entire history command will show)
$ history
...
If, on the other hand, you typed hi and then tab twice, you would see this:
$ hi (then the tab key twice)
hipercdecode hipsopgm history
$ hi
The shell is telling you that there are three commands that start with hi, and
you have to continue with the letter you know is next. Then, if you type tab
again, you can finish the completion.
Tab completion is extra-handy when you want to type file names or directories.
Instead of typing a long file name, you can simply start typing a name and then
type tab to have the name autocomplete. If only part of the name completes,
that means there are multiple options, and typing tab again will give you
the options that the shell is considering.
Using tab completion, you can quickly type long paths, and you don't have to type many characters at all.