Unix filesystem: Difference between revisions

Revision as of 18:35, 30 January 2019

Revision as of 17:22, 16 February 2019

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===File types===

{{Main article |Unix file types}}

The original Unix file system supported three types of files: ordinary files, [[Directory (computing)|directories]], and "special files", also termed device files.<ref name="Ritchie"/> The [[Berkeley Software Distribution]] (BSD) and [[UNIX System V|System V]] each added a file type to be used for [[interprocess communication]]: BSD added [[Berkeley sockets|sockets]],<ref name="43bsd">{{cite book |last1= Leffler|first1= Samuel J. |authorlink1= Samuel J Leffler |last2= McKusick |first2= Marshall Kirk|authorlink2= Marshall Kirk McKusick |last3= Karels |first3= Michael J. |authorlink3=Michael J. Karels |last4=Quarterman |first4= John S. |authorlink4= John Quarterman |title= The Design and Implementation of the [[Berkeley Software Distribution|4.3BSD UNIX]] Operating System|date=October 1989| publisher= [[Addison-Wesley]]|isbn= 0-201-06196-1}}</ref> while System V added [[Named pipe#In Unix|FIFO files]].

BSD also added [[symbolic link]]s (often termed "symlinks") to the range of file types, which are files that refer to other files, and complement hard links.<ref name="43bsd"/> Symlinks were modeled after a similar feature in [[Multics]],<ref name="FFS">{{cite web|last1=McKusick et al|display-authors=etal|first1=Marshall Kirk|title=A Fast Filesystem for Unix|url=https://docs.freebsd.org/44doc/smm/05.fastfs/paper.pdf|website=Freebsd.org|publisher=CSRG, UC Berkeley|accessdate=16 November 2016}}</ref> and differ from hard links in that they may span filesystems and that their existence is independent of the target object. Other Unix systems may support additional types of files.<ref>{{man|2|stat|Linux}}</ref>

==Conventional directory layout==