share (command)

In computing, share is a command for DOS that allows software to perform file locks. Locking files became necessary when MS-DOS began allowing files to be accessed simultaneously by multiple programs, either through multitasking or networking.[1][2][3]

share

Developer(s)	Microsoft, Paragon Technology Systems, DR, Datalight, Novell, Ron Cemer
Initial release	1984, 35–36 years ago
Operating system	MS-DOS, PTS-DOS, SISNE plus, Windows, DR DOS, ROM-DOS, FreeDOS
Type	Command

Implementations

On MS-DOS, the command is available in versions 3 and later.[4] The command is also available in FreeDOS,[5] PTS-DOS,[6] and SISNE plus.[7] The FreeDOS version was developed by Ron Cemer and is licensed under the GPL.[8] DR DOS 6.0[9] and Datalight ROM-DOS[10] include an implementation of the share command.

Windows XP and later versions include 16-bit commands (nonnative) for the MS-DOS subsystem that are included to maintain MS-DOS compatibility. The share MS-DOS subsystem command performs functions that are now inherent to Microsoft Windows. It is available to preserve compatibility with existing files, but has no effect at the command line because the functionality is automatic. The 16-bit MS-DOS subsystem commands are not available on 64-bit editions of Windows.[11]

Design

There were five locking modes:

• Deny None
• Deny Read
• Deny Write
• Deny All
• Compatibility (designed for backward compatibility with existing MS-DOS programs)

The program runs as a Terminate and Stay Resident program and is typically loaded at boot-up.

Syntax

share [/F:space] [/L:locks]

• /F:space Allocates file space (in bytes) for file-sharing information.
• /L:locks Sets the number of files that can be locked at one time.

See also

• List of DOS commands

References

1. Jamsa, Kris A. (1993), DOS: The Complete Reference, Osborne McGraw-Hill, p. 206, ISBN 0078819040.
2. http://www.easydos.com/share.html
3. MS-DOS and Windows command line share command
4. Wolverton, Van (2003). Running MS-DOS Version 6.22 (20th Anniversary Edition), 6th Revised edition. Microsoft Press. ISBN 0-7356-1812-7.
5. http://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/1.2/repos/pkg-html/group-base.html
6. "PTS-DOS 2000 Pro User Manual" (PDF). Buggingen, Germany: Paragon Technology GmbH. 1999. Archived (PDF) from the original on 2018-05-12. Retrieved 2018-05-12.
7. SISNE plus - Referência Sumária | Datassette
8. http://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/1.2/repos/pkg-html/share.html
9. DR DOS 6.0 User Guide Optimisation and Configuration Tips
10. "Datalight ROM-DOS User's Guide" (PDF). www.datalight.com.
11. MS-DOS subsystem commands

Further reading

• Cooper, Jim (2001). Special Edition Using MS-DOS 6.22, Third Edition. Que Publishing. ISBN 978-0789725738.