FreeBSD man pages : pwd_mkdb (8)
PWD_MKDB(8) FreeBSD System Manager's Manual PWD_MKDB(8)
pwd_mkdb - generate the password databases
pwd_mkdb [-C] [-N] [-p] [-d directory] [-s cachesize] [-u username] file
The pwd_mkdb utility creates db(3) style secure and insecure databases
for the specified 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:
-C Check if the password file is in the correct format. Do not
change, add, or remove any files.
-N Tell pwd_mkdb to exit with an error if it cannot obtain a lock on
the file. By default, we block waiting for a lock on the source
file. The lock is held through the rebuilding of the database.
-p Create a Version 7 style password file and install it into
Store databases into specified destination directory instead of
Only update the record for the specified user. Utilities that
operate on a single user can use this option to avoid the overhead
of rebuilding the entire database.
Specify in megabytes the size of the memory cache 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. The default
is 2 megabytes.
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
The pwd_mkdb utility exits zero on success, non-zero on failure.
If the PW_SCAN_BIG_IDS environment variable is set, pwd_mkdb will sup-
press the warning messages that are normally generated for large user and
group IDs. Such IDs can cause serious problems with software that makes
assumptions about the values of IDs.
/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.
/etc/master.passwd The current password file.
/etc/passwd A Version 7 format password file.
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 pwd_mkdb,
chpass(1), passwd(1) and vipw(8), handle the locking necessary to avoid
Previous versions of the system had a program similar to pwd_mkdb,
mkpasswd(8), which built dbm(3) style databases for the password file but
depended on the calling programs to install them. The program was
renamed in order that previous users of the program not be surprised by
the changes in functionality.
chpass(1), passwd(1), db(3), getpwent(3), passwd(5), vipw(8)
FreeBSD 4.8 June 6, 1993 FreeBSD 4.8