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(bashref.info)Definitions

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Definitions
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   These definitions are used throughout the remainder of this manual.

`POSIX'
     A family of open system standards based on Unix.  Bash is
     concerned with POSIX 1003.2, the Shell and Tools Standard.

`blank'
     A space or tab character.

`builtin'
     A command that is implemented internally by the shell itself,
     rather than by an executable program somewhere in the file system.

`control operator'
     A `word' that performs a control function.  It is a `newline' or
     one of the following: `||', `&&', `&', `;', `;;', `|', `(', or `)'.

`exit status'
     The value returned by a command to its caller.  The value is
     restricted to eight bits, so the maximum value is 255.

`field'
     A unit of text that is the result of one of the shell expansions.
     After expansion, when executing a command, the resulting fields
     are used as the command name and arguments.

`filename'
     A string of characters used to identify a file.

`job'
     A set of processes comprising a pipeline, and any processes
     descended from it, that are all in the same process group.

`job control'
     A mechanism by which users can selectively stop (suspend) and
     restart (resume) execution of processes.

`metacharacter'
     A character that, when unquoted, separates words.  A metacharacter
     is a `blank' or one of the following characters: `|', `&', `;',
     `(', `)', `<', or `>'.

`name'
     A `word' consisting solely of letters, numbers, and underscores,
     and beginning with a letter or underscore.  `Name's are used as
     shell variable and function names.  Also referred to as an
     `identifier'.

`operator'
     A `control operator' or a `redirection operator'.  Note:
     Redirections, for a list of redirection operators.

`process group'
     A collection of related processes each having the same process
     group ID.

`process group ID'
     A unique identifer that represents a `process group' during its
     lifetime.

`reserved word'
     A `word' that has a special meaning to the shell.  Most reserved
     words introduce shell flow control constructs, such as `for' and
     `while'.

`return status'
     A synonym for `exit status'.

`signal'
     A mechanism by which a process may be notified by the kernel of an
     event occurring in the system.

`special builtin'
     A shell builtin command that has been classified as special by the
     POSIX 1003.2 standard.

`token'
     A sequence of characters considered a single unit by the shell.
     It is either a `word' or an `operator'.

`word'
     A `token' that is not an `operator'.