Bash (Unix shell): Difference between revisions

Revision as of 01:02, 26 August 2025

Revision as of 01:04, 26 August 2025

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}}</ref>

=== TokenizationTokens <span class="anchor" id="Syntax"></span><span class="anchor" id="Tokens"></span><span class="anchor" id="Metacharacters"></span><span class="anchor" id="Operators"></span><span class="anchor" id="Words"></span><span class="anchor" id="Names"></span> ===

: <syntaxhighlight lang = text>

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When Bash reads a full commandline, the complete string is broken down according to a certain set of rules into individual units called ''tokens.''

''Tokens'' are identified using, and separated from each other using ''metacharacters.'' (As of version 5.3:)

* The ten ''"metacharacters:"''

: {{Pre |‘space’ ‘tab’ ‘newline’ ‘|’ ‘&’ ‘;’ ‘(’ ‘)’ ‘<’ ‘>’}}

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From there it further breaks ''words'' down into more specific, meaningful pieces like command names, variable assignment statements, etc.

* The two ''Blanks"blanks"''

: {{Pre |‘space’ ‘tab’}}

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* ''Operators''

:* Eight of the twelve ''"control operators:"''

:* ''Control Operators''

:: <syntaxhighlight lang = text>

‘newline’ ‘||’ ‘&&’ ‘&’ ‘;’ ‘;;’ ‘;&’ ‘;;&|’ ‘||’ ‘|&&’ ‘(’ ‘)’ ...

</syntaxhighlight>

:* Five of the fourteen ''"redirection operators:"''

:* ''Redirection Operators''

:: <syntaxhighlight lang = text>

‘<’ ‘<>’ ‘>’ ‘>|’ ‘&>>’ ‘&>’ ‘>&’ ‘<&<’ ‘<<’ ‘<<-’ ‘<<<’...

</syntaxhighlight>

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* ''Words''

:* Sixteen of the twenty-two ''reserved words,'' which may be characters or words:

:* ''Reserved Words''

:: <syntaxhighlight lang = bash>

‘!’ ‘[[’ ‘{’ ‘]]’ ‘}’ coproc case do done else elifin esac fi for functiondo done if inthen timeelif selectelse then untilfi while...

</syntaxhighlight>