login-utils/passwd.1

   1 .\" Copyright 1992 Rickard E. Faith (faith@cs.unc.edu)
   2 .\" May be distributed under the GNU General Public License
   3 .TH PASSWD 1 "11 November 1996" "Util-linux 2.6" "Linux Programmer's Manual"
   4 .SH NAME
   5 passwd \- change password
   6 .SH SYNOPSIS
   7 .BR "passwd"
   8 .RB [ " \-o " ]
   9 .RB [ " \-q " ]
  10 .RB [ " \-v " ]
  11 .RI [ " name " [ " password " ]]
  12 .br
  13 .BR "passwd \-f "
  14 .RI [ " arguments to chfn " ]
  15 .br
  16 .BR "passwd \-s "
  17 .RI [ " arguments to chsh " ]
  18
  19 .SH DESCRIPTION
  20 Without arguments
  21 .B passwd
  22 will change the password for the current user. First the user is asked for
  23 the old password, then prompted twice for the new password in order to
  24 catch typing errors.
  25
  26 The one and two argument forms may only be used by the superuser. Using the
  27 one argument form, the superuser may change the password for that
  28 .IR user .
  29 The superuser is not asked for the users old password, but the rules
  30 for proper passwords are also applied unless the
  31 .B "\-o"
  32 option is used. The superuser may have legitimate
  33 reasons to choose a non-conformant password.
  34
  35 The two argument form gives the
  36 .IR user " the " password
  37 stated as the second argument. This may be useful when giving many
  38 users an initial generated password.  But it can also be extremely
  39 dangerous.  A simple script bug might change to root password to
  40 something unknown.
  41
  42 Giving an empty string as the second argument erases the password for the
  43 user, but only in combination with the
  44 .B "\-o"
  45 option.
  46
  47 Password changes may get logged using the
  48 .BR syslog (3)
  49 facility, depending on compile-time defines (on by default).
  50 If so, every change will
  51 be logged at a low level as auth.notice, except for changing the root
  52 password with will be logged with auth.warning.
  53
  54 .SH OPTIONS
  55 .TP
  56 .B "\-f, \-\-fullname"
  57 Change the user's full name (the GECOS field of the passwd entry).
  58 Invokes /usr/bin/chfn with the non-option command line arguments.
  59 .TP
  60 .B "\-o, \-\-force"
  61 Turn off simplicity checks on the new password. This option may only
  62 be used by the super user. This is intend to allow simple initial
  63 passwords given by the superuser.
  64 .TP
  65 .B "\-s, \-\-shell"
  66 Change the user's shell by invoking /usr/bin/chsh with the non-option
  67 command line arguments.
  68 .TP
  69 .B "\-q, \-\-quiet, \-\-silent"
  70 In this mode passwd won't tell that the passwd get's changed.
  71 .TP
  72 .B "\-v, \-V, \-\-version"
  73 Prints version information and exits.
  74
  75 .SH PASSWORD RULES
  76 The new password must fulfill these rules:
  77 .TP
  78 o
  79 be at least six characters long;
  80
  81 .TP
  82 o
  83 must not be equal to the old password;
  84
  85 .TP
  86 o
  87 must contain characters out of at least two of the following classes:
  88 upper and lower case letters, digits and non alphanumeric characters;
  89
  90 .TP
  91 o
  92 must not match neither the username nor any word of the realname,
  93 neither in normal nor in reverse order, neither at the beginning nor
  94 at the end.
  95 .SH FILES
  96 .TP
  97 .I /etc/passwd
  98 The password file.
  99 .SH "SEE ALSO"
 100 .BR chsh (1),
 101 .BR chfn (1),
 102 .BR syslog (3),
 103 .BR syslog.conf (5),
 104 .BR passwd (8).
 105 .SH AUTHOR
 106 Peter Orbaek (poe@daimi.aau.dk).
 107 .br
 108 Martin Schulze (joey@infodrom.north.de) with extensive rewriting and
 109 improving done.
 110 .br
 111 .SH MAINTAINER
 112 Nicolai Langfeldt (janl@math.uio.no)