Learning the Unix Operating System, 5th Edition

Glossary

alphanumeric

Characters: letters (alpha) and numbers (numeric), including punctuation characters (such as _ and ?).

click

Depress and quickly release a mouse button; double- and triple-click imply depressing and releasing a mouse button two or three times, respectively, within a short period. You’ll usually click with the first mouse button (which is the left mouse button for righthanded users—or the opposite if your mouse has been configured for a lefthanded user). See also point.

clipboard

A temporary storage area for X Window System programs, used for transferring text (“copying” and “pasting” text) between programs.

command

A command is an instruction that you can give to a program running on the Unix system. For instance, you can type a program’s name and arguments on a command line, at a shell prompt; this command asks the shell to run that program. (The shell is a program itself; see shell.) Once a program starts running, it may accept commands of its own. For example, a text editor has commands for deleting and adding text to the file it’s editing.

The terms command and program are used almost interchangeably, probably because the program name is typed first on a command line (at a shell prompt). Shells have some built-in commands that don’t start a separate program running; one of these is cd, which changes the shell’s working directory.

cracker

A malicious person who tries to break into computer systems (usually via a network), disrupt computers and ...