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PWD_MKDB(8)		  BSD System Manager's Manual		   PWD_MKDB(8)

     pwd_mkdb -- generate the password databases

     pwd_mkdb [-BLlpsvw] [-c cachesize]	[-d directory] [-u username]
	      [-V version] file

     pwd_mkdb creates db(3) style secure and insecure databases	for the	speci-
     fied file.	 These databases are then installed into "/etc/spwd.db"	and
     "/etc/pwd.db" respectively.  The file is installed	into
     "/etc/master.passwd".  The	file must be in	the correct format (see
     passwd(5)).  It is	important to note that the format used in this system
     is	different from the historic Version 7 style format.

     The options are as	follows:

     -B	   Store data in big-endian format (see	also -L).

     -c	cachesize
	   Specify the size of the memory cache	in megabytes used by the hash-
	   ing library.	 On systems with a large user base, a small cache size
	   can lead to prohibitively long database file	rebuild	times.	As a
	   rough guide,	the memory usage of pwd_mkdb in	megabytes will be a
	   little bit more than	twice the figure specified here.  If unspeci-
	   fied, this value will be calculated based on	the size of the	input
	   file	up to a	maximum	of 8 megabytes.

     -d	directory
	   Change the root directory of	the generated files from "/" to

     -L	   Store data in little-endian format (see also	-B).

     -l	   Use syslog(3) to report errors.

     -p	   Create a Version 7 style password file and install it into

     -s	   Update the secure database only.  This is useful when only en-
	   crypted passwords have changed.  This option	negates	the effect of
	   any -p option.

     -u	name
	   Don't re-build the database files, but instead modify or add	en-
	   tries for the specified user	only.  This option may only be used
	   when	the line number	and user name in the password file have	not
	   changed, or when adding a new user from the last line in the	pass-
	   word	file.

     -V	version
	   Upgrade or downgrade	databases to the numbered version.  Version 0
	   is the old format (up to and	including NetBSD 5.0) with the 4 byte
	   time	fields and version 1 is	the new	format with the	8 byte time
	   fields (greater than	NetBSD 5.0).  NetBSD 5.0 cannot	read version 1
	   databases.  All versions above NetBSD 5.0 can read and write	both
	   version 0 and version 1 databases.  By default the databases	stay
	   in the version they were before the command was run.

     -v	   Mention when	a version change occurs.

     -w	   Print a warning if the system is using old style databases.

     The two databases differ in that the secure version contains the user's
     encrypted password	and the	insecure version has an	asterisk ("*").

     The databases are used by the C library password routines (see

     /etc/master.passwd		       The current password file.
     /etc/passwd		       A Version 7 format password file.
     /etc/pwd.db		       The insecure password database file.
     /etc/pwd.db.tmp		       A temporary file.
     /etc/spwd.db		       The secure password database file.
     /etc/spwd.db.tmp		       A temporary file.

     pwd_mkdb exits zero on success, non-zero on failure.

     Previous versions of the system had a program similar to pwd_mkdb which
     built dbm style databases for the password	file but depended on the call-
     ing programs to install them.  The	program	was renamed in order that pre-
     vious users of the	program	not be surprised by the	changes	in functional-

     chpass(1),	passwd(1), pwhash(1), db(3), getpwent(3), pw_mkdb(3),
     syslog(3),	passwd(5), useradd(8), userdel(8), usermod(8), vipw(8)

     Because of	the necessity for atomic update	of the password	files,
     pwd_mkdb uses rename(2) to	install	them.  This, however, requires that
     the file specified	on the command line live on the	same file system as
     the "/etc"	directory.

     There are the obvious races with multiple people running pwd_mkdb on dif-
     ferent password files at the same time.  The front-ends to	chpass(1),
     passwd(1),	useradd(8), userdel(8),	usermod(8), and	vipw(8)	handle the
     locking necessary to avoid	this problem.

     The database files	are copied when	the -u option is used.	Real locking
     would make	this unnecessary.

     Although the DB format is endian-transparent, the data stored in the DB
     is	not.  Also, the	format doesn't lend itself to insertion	or removal of
     records from arbitrary locations in the password file.  This is difficult
     to	fix without breaking compatibility.

     Using the -u option on a system where multiple users share	the same UID
     can have unexpected results.

BSD				August 18, 2010				   BSD


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