passwd(F)                     06 January 1993                      passwd(F)


 Name

    passwd - password file

 Format

    username:password:UID:GID:comment:directory:program

 Description

    passwd is an ASCII file. Each entry in passwd occupies one line and
    describes one user. Each line contains the following seven colon-
    separated fields:

    username  The login name of the user.

    password  Encrypted password.  If this field is null, no password is
              demanded.  If the shadow file exists on the system, then an x
              is stored in this field; the encrypted password and password
              aging information are stored in the shadow(F) file instead.

    UID       Numerical user ID.

    GID       Numerical group ID as defined in the group(F) file.

    comment   This field corresponds to the information displayed as the out-
              put of the finger command. Refer to finger(C) for details of
              the required format.

    directory Initial working directory

    program   Program to use as shell.  If this field is null, sh(C) is used
              by default.

    Passwords are encrypted, so passwd has general read permission and can be
    used, for example, to map numerical user IDs to names.

    The encrypted password consists of 13 characters chosen from a 64-
    character alphabet (., /, 0-9, A-Z, a-z).  In the case that the password
    is null, the encrypted password is also null.

    Password aging

    Password aging is in effect for a particular user if their encrypted
    password is followed by a comma and a non-null string of characters from
    the above alphabet. (Such a string must be introduced by the super user.)

    The first character of the age denotes the maximum number of weeks for
    which a password is valid.  A user who attempts to log in after his pass-
    word has expired will be forced to supply a new one.

    The next character denotes the minimum period in weeks which must expire
    before the password may be changed.

    The remaining characters define the week (counted from the beginning of
    1970) when the password was last changed. (A null string is equivalent to
    zero.)

    The first and second characters must have numerical values in the range
    0-63, where the dot (.) is equal to 0 and lowercase z is equal to 63.

    If the numerical value of both characters is 0, the user will be forced
    to change his password the next time he logs in.

    If the second character is greater than the first, only the super user
    will be able to change the password.

 Files

    /etc/passwd    full pathname of passwd

 See also

    getprpwent(S), getpwent(S), group(F), login(M), passwd(C), pwconv(ADM),
    shadow(F)