Editing File copying

{{short description|Act of creating a new computer file with content matching an exiting file}}
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In [[computing]], '''file copying''' is the act of creating a new [[Computer file|file]] such that it has the same content as an existing file. The operation is sometimes called ''cloning''. 

Generally, an [[operating system]] [[command-line]] [[shell (computing)|shell]] provides for file copying via commands  <code>[[cp (Unix)|cp]]</code>, <code>[[COPY (command)|copy]]</code> and similar variants.  <code>[[mv (Unix)|mv]]</code> also copies files but only when the source and destination are on different [[file system]]s. [[Windows]] also provides includes the more advanced tools: [[Robocopy]] and [[xcopy]].

Many operating systems also provide for copying files via a [[graphical user interface]], such as a [[file manager]]. It may provide for [[copy-and-paste]] and [[drag-and-drop]] [[user experience]]. 

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Notable third-party utilities:
* [[FastCopy]]
* [[Rclone]]
* [[RichCopy]]
* [[rsync]]
* [[TeraCopy]]
* [[Ultracopier]]

== Shadow copy ==
Shadowing describes the process of maintaining a copy of a set of files, a.k.a. to [[Disk mirroring|mirror]] files in a separate physical location. Depending on the reasons behind the shadow operation, this location may be as close as the [[BIOS]] chip to the [[RAM]] modules or as far away as the other side of the [[Earth|globe]].

== Remote copy ==
{{anchor|NCOPY}}
Some systems have specialized [[system call]]s for copying files (like {{code|CopyFile}} in [[Windows API]]), while others (like Unix-based and DOS) simply read the contents of the existing file into memory and write it to a new file. A specialized system call provides little advantage for files on local [[computer storage|storage]], but can optimize operation when the source and target files are on a remote [[file server]]. The system call can tell the server to process the files on the server's file system; without sending file content over the network; thus greatly improving performance. Lacking such file server support, copying requires reading file content over the network, and sending it back over the network again. 

Sometimes, remote file copying is performed with a specialized command, like {{code|NCOPY}} in DOS clients for [[Novell NetWare]]. The [[COPY (DOS command)|COPY]] command in some versions of [[DR-DOS]] since 1992,<ref name="Caldera_1997_DOSSRC"/> has built-in support for this.
An even more complicated situation arises when one needs to copy files between two remote servers. The simple way is to read data from one server, and then to write the data to the second server.

== See also ==
* {{section link|Computer file#Moving methods}}
* [[Backup software]]
* [[Disk cloning]]
* [[Disk mirroring]]
* [[File synchronization]]
* [[Hard copy]]
* [[ln (Unix)]]
* [[NTFS junction point]]
* [[Optical disc authoring]]
* [[Peripheral Interchange Program]]
* [[Zero copy]]

== References ==
{{Reflist|refs=
<ref name="Caldera_1997_DOSSRC">{{cite web |title=Caldera OpenDOS Machine Readable Source Kit (M.R.S) 7.01 |publisher=[[Caldera (company)|Caldera, Inc.]] |date=1997-05-01 |url=https://archive.sundby.com/retro/DR-DOS/dossrc.zip |access-date=2022-01-02 |url-status=live |archive-url=https://web.archive.org/web/20210807095409/https://archive.sundby.com/retro/DR-DOS/dossrc.zip |archive-date=2021-08-07}}  [https://web.archive.org/web/20220102102656/https://archive.sundby.com/retro/OpenDOS/OPENDOS_7.01_CODE.ZIP] (NB. Actually implemented since [[DR DOS "Panther"]] on 1992-06-22, see COMCPY.C/DOSIF.ASM in the COMMAND.COM sources of [[OpenDOS 7.01]].)</ref>
}}

== Further reading ==
* [http://www.freepatentsonline.com/5043876.html N-level file shadowing and recovery in a shared file system], United States Patent 5043876
* [http://www.freepatentsonline.com/5276871.html Method of file shadowing among peer systems], United States Patent 5276871
* [https://web.archive.org/web/20061127130733/http://www.ibexpert.info/documentation/%20%209.%20IBExpert%20Services%20Menu/%20%202.%20Restore%20Database/%20%201.%20Database%20Shadow%20Files/15713.html Database Shadow Files]

== External links ==
* [https://www.gnu.org/software/emacs/manual/html_node/emacs/File-Shadowing.html Instructions on how to shadow files] for [[Emacs]]
{{Computer files}}

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[[Category:Computer file systems]]
[[Category:Copyright law]]