Interpreter directive: Difference between revisions
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#REDIRECT [[Directive (programming)]] |
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{{short description|Computer language construct to control an interpreter}} |
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{{Confusing|date=February 2016}} |
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An '''interpreter directive''' is a [[computer language]] construct, that on some systems is better described as an aspect of the system's executable file format, that is used to control which [[Interpreter (computing)|interpreter]] parses and interprets the instructions in a [[computer program]].<ref>{{cite book|last1= Weik |first1= Martin H. |title= Computer Science and Communications Dictionary |url= https://books.google.com/books?id=gbP1bLDPKlYC&pg=PA829 |volume= 1 |year= 2000 |publisher= [[Springer Science+Business Media|Springer]] |isbn= 978-0-7923-8425-0 |page= 829 }}</ref> |
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In [[Unix]], [[Linux]] and other [[Unix-like]] [[operating system]]s, the first two bytes in a file can be the characters "#!", which constitute a [[magic number (programming)|magic number]] ([[hexadecimal]] 23 and 21, the ASCII values of "#" and "!") often referred to as [[Shebang (Unix)|shebang]], prefix the first line in a [[script (Unix)|script]], with the remainder of the line being a command usually limited to a max of 14 (when introduced) up to usually about 80 characters in 2016{{Citation needed|date = May 2016}}. If the [[file system permissions]] on the script (a file) include an [[Execution (computing)|execute]] permission bit for the user invoking it by its filename (often found through the command search path), it is used to tell the operating system what interpreter (usually a program that implements a [[scripting language]]) to use to execute the [[Shell script|script]]'s contents, which may be [[Batch processing|batch commands]] or might be intended for interactive use. An example would be ''#!/bin/bash'', meaning run this script with the [[Bash (Unix shell)|bash shell]] found in the /bin [[Unix filesystem#Conventional directory layout|directory]].<ref>{{cite web|title=Advanced Bash Scripting Guide|url=http://tldp.org/LDP/abs/html/sha-bang.html|access-date=2012-01-19}}</ref><ref>{{cite book |
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|last=Cooper |
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|first=Mendel |
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|title=Advanced Bash Scripting Guide 5.3 Volume 1 |
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|publisher=lulu.com |
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|date=November 5, 2010 |
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|isbn=978-1-4357-5218-4 |
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|page=5 |
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|url=https://books.google.com/books?id=WPXkgFRd4OEC&q=sha-bang&pg=PA5 |
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}}</ref><ref>{{cite book |
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|last=MacDonald |
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|first=Matthew |
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|title=HTML5: The Missing Manual |
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|publisher=[[O'Reilly Media]] |
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|location=Sebastopol, California |
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|year=2011 |
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|isbn=978-1-4493-0239-9 |
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|page=373 |
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|url=https://books.google.com/books?id=SR7HXy2XvBEC&pg=PA373 |
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}}</ref><ref>{{cite book |
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|last=Lutz |
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|first=Mark |
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|title=Learning Python |
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|edition=4th |
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|publisher=[[O'Reilly Media]] |
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|date=September 2009 |
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|isbn=978-0-596-15806-4 |
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|page=48 |
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|url=https://books.google.com/books?id=1HxWGezDZcgC&pg=PA48 |
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}}</ref><ref>{{cite book |
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|last=Lie Hetland |
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|first=Magnus |
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|title=Beginning Python: From Novice to Professional |
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|publisher=Apress |
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|date=October 4, 2005 |
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|isbn=978-1-59059-519-0 |
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|page=21 |
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|url=https://books.google.com/books?id=S0l1YFpRFVAC&q=pound+bang&pg=PA21 |
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}}</ref><ref>{{cite book |
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|last=Schitka |
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|first=John |
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|title=Linux+ Guide to Linux Certification |
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|publisher=Course Technology |
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|date=December 24, 2002 |
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|isbn=978-0-619-13004-6 |
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|page=353 |
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|url=https://books.google.com/books?id=l7JhL9rJLEgC&q=hashpling&pg=PA353 |
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}}</ref> |
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Other systems or files may use some other ''[[Magic number (programming)|magic number]]'' as the interpreter directives. |
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== See also == |
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* [[Architecture description language]] |
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* [[Bourne shell]] |
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* [[C shell]] |
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* [[Command-line interface#Command-line interpreter]] |
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* [[Filename extension#Command name issues]] |
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* [[Shebang (Unix)]] |
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* [[Unix shell]] |
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== References == |
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{{Reflist|35em}} |
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{{DEFAULTSORT:Interpreter Directive}} |
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[[Category:Command shells]] |
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[[Category:Computing terminology]] |
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{{Computing-stub}} |
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Revision as of 03:31, 25 February 2023
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