Wheel (Unix term)

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In computing, the term wheel refers to a user account with a wheel bit, a system setting that provides additional special system privileges that empower a user to execute restricted commands that ordinary user accounts cannot access.[1][2] The term is derived from the slang phrase big wheel, referring to a person with great power or influence.[1] It was first used in this context with regard to the TENEX operating system, later distributed under the name TOPS-20 in the 1960s and early 1970s.[2][3]

The term was adopted by Unix users in the 1980s, due to the movement of operating system developers and users from TENEX/TOPS-20 to Unix.[2] Modern Unix implementations generally include a security protocol that requires a user to be a member of the wheel user privileges group in order to gain superuser access to a machine by using the su command.[1][2][4]

Wheel group[edit]

Modern Unix systems use user groups to control access privileges. The wheel group is a special user group used on some Unix systems to control access to the su command, which allows a user to masquerade as another user (usually the super user).

Wheel war[edit]

The related phrase wheel war was used in Stanford University culture to refer to system disruption caused by students gaining wheel access in order to lock other students out or erase their files, with collateral damage caused to the work of other uninvolved users of the system.[5]


  1. ^ a b c "Wheel". Jargon File 4.2.0. Dictionary.com. Retrieved 2008-09-12. 
  2. ^ a b c d "Wheel bit". Jargon File 4.2.0. Dictionary.com. Retrieved 2008-09-12. 
  3. ^ "TWENEX". Jargon File 4.4.7. Eric Raymond. Retrieved 2008-09-12. 
  4. ^ Levi, Bozidar (2002). UNIX Administration: A Comprehensive Sourcebook for Effective Systems and Network Management. CRC Press. p. 207. ISBN 0-8493-1351-1. 
  5. ^ "Wheel war". Jargon File 4.4.7. Eric Raymond. Retrieved 2008-09-12.