CLS (command) explained

cls
Developer:	DEC, Microsoft, IBM, TSL, DR, Novell, Toshiba, ReactOS Contributors
Operating System:	RT-11, DOS, MSX-DOS, FlexOS, PC-MOS, SISNE plus, OS/2, Windows, ReactOS, SymbOS, DexOS
Platform:	Cross-platform
Genre:	Command
License:	PC-MOS: GPL v3 ReactOS: GPL v2

In computing, CLS (for clear screen) is a command used by the command-line interpreters [[COMMAND.COM]] and [[cmd.exe]] on DOS, Digital Research FlexOS,^[1] IBM OS/2,^[2] Microsoft Windows^[3] and ReactOS operating systems to clear the screen or console window of commands and any output generated by them. It does not clear the user's history of commands, however.The command is also available in the DEC RT-11 operating system, in the open-source MS-DOS emulator DOSBox and in the EFI shell.^[4] In other environments, such as Linux and Unix, the same functionality is provided by the [[clear (Unix)|clear]] command.

History

The command is available in MS-DOS versions 2 (1983) and later.^[5] While the ultimate origins of using the three-character string CLS as the command to clear the screen likely predate Microsoft's use, this command was present before its MS-DOS usage, in the embedded ROM BASIC dialects Microsoft wrote for early 8-bit microcomputers (such as TRS-80 Color BASIC), where it served the same purpose. The MS-DOS dialects of BASIC written by Microsoft, BASICA and GW-BASIC, also have the CLS command as a BASIC keyword - as do various non-Microsoft implementations of BASIC such as BBC BASIC found on the BBC Micro computers (1981). The CLS command is also present in BASIC versions for Microsoft Windows, however this generally clears text printed on the form, rather than the whole window or controls on the form.

The command CLS has appeared as a clear screen command in many other BASIC dialects and command line interpreters, because of its familiarity through being included in MS-DOS.

The Software Link's PC-MOS includes an implementation of CLS.^[6] Like the rest of the operating system, it is licensed under the GPL v3.^[7]

DR DOS also includes an implementation of the command.^[8]

See also

• CLS (CONFIG.SYS directive)
• List of DOS commands

Further reading

• Book: Wolverton. Van. MS-DOS Commands: Microsoft Quick Reference, 4th Revised edition. registration. 1990. Microsoft Press. 978-1556152894.
• Book: Kathy Ivens. Brian Proffit. 1993. OS/2 Inside & Out. Osborne McGraw-Hill. 978-0078818714.
• Book: Frisch, Æleen. 2001. Windows 2000 Commands Pocket Reference. O'Reilly. 978-0-596-00148-3.

External links

• cls | Microsoft Docs

Notes and References

1. http://www.bitsavers.org/pdf/digitalResearch/flexos/1073-2003_FlexOS_Users_Guide_V1.3_Nov86.pdf
2. Web site: JaTomes Help - OS/2 Commands . 2019-07-06 . 2019-04-14 . https://web.archive.org/web/20190414130029/http://www.jatomes.com/Help/Os2Cmd.php#CLS . dead .
3. https://technet.microsoft.com/en-us/library/bb490879.aspx Microsoft TechNet Cls article
4. Web site: EFI Shells and Scripting . . 2013-09-25.
5. Book: Wolverton. Van. Running MS-DOS Version 6.22 (20th Anniversary Edition), 6th Revised edition. 2003. Microsoft Press. 0-7356-1812-7.
6. https://github.com/roelandjansen/pcmos386v501/blob/master/DOCS/v4/PCMOSv4UserManual.pdf PC-MOS User Guide
7. Web site: pcmos386v501: PC-MOS/386 v5.01 final release including cdrom driver sources. Roeland. Jansen. 8 February 2018. GitHub.
8. Web site: DR DOS 6.0 User Guide Optimisation and Configuration Tips . 2019-08-13 . https://web.archive.org/web/20190930135943/http://www.4corn.co.uk/archive/docs/DR%20DOS%206.0%20User%20Guide-opt.pdf . 2019-09-30 . dead .