Gecos stands for General Electric Comprehensive Operating Supervisor.

The GECOS field in POSIX was created to hold non-unix attributes required by the GE COS operating system, because Denis Ritchie and Ken Thompson could not afford a printer, and had to print through a GCOS system, which required user attributes Unix does not use. Those attributes were stuffed into the GECOS field.

Today the GECOS field is subfielded, holding multiple data items, which might include the common name associated with the user of a POSIX account, as well as things like office location, extension, and home phone.

Tools like

  • finger
  • chfn
  • adduser
expect subfields within the GECOS field, separated by commas.

The typical format for the GECOS field is a comma-delimited list with this order:

  • User's full name (or application name, if the account is for a program)
  • Building and room number or contact person
  • Office telephone number
  • Any other contact information (pager number, fax, etc.)
In most UNIX systems normal users can change their own information using the chfn or chsh command.

LDAP Attribute Definition#

The Gecos AttributeTypes is defined as:

More Information#

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