UNIX user accounts

The traditional UNIX user account database is the file /etc/passwd. Each record is a line of fields separated by the ':' character:

name:passwd:uid:gid:gecos:dir:shell

name

The user's login name, traditionally limited to 8 characters but often longer in more modern systems.

passwd

Traditionally the encrypted user password, now usually found in /etc/shadow instead.

uid, gid

Numeric user id and primary group id of the user.

gecos

The user's real name and possibly other information like a phone number or office location (GECOS was another operating system used at Bell Labs and this field was originally data from a user's GECOS account).

dir

The user's home directory, the default location for other user-specific configuration information.

shell

The user's shell (specified by full pathname).

BSD systems use a similar /etc/master.passwd file that is used to generate a traditional-format /etc/passwd file.

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