minix/usr.sbin/pwd_mkdb/pwd_mkdb.8

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.\"	from: @(#)pwd_mkdb.8	8.2 (Berkeley) 4/27/95
.\"
.Dd August 18, 2010
.Dt PWD_MKDB 8
.Os
.Sh NAME
.Nm pwd_mkdb
.Nd generate the password databases
.Sh SYNOPSIS
.Nm
.Op Fl BLlpsvw
.Op Fl c Ar cachesize
.Op Fl d Ar directory
.Op Fl u Ar username
.Op Fl V Ar version
.Ar file
.Sh DESCRIPTION
.Nm
creates
.Xr db 3
style secure and insecure databases for the specified file.
These databases are then installed into
.Dq Pa /etc/spwd.db
and
.Dq Pa /etc/pwd.db
respectively.
The file is installed into
.Dq Pa /etc/master.passwd .
The file must be in the correct format (see
.Xr passwd 5 ) .
It is important to note that the format used in this system is
different from the historic Version 7 style format.
.Pp
The options are as follows:
.Bl -tag -width flag
.It Fl B
Store data in big-endian format (see also
.Fl L ) .
.It Fl c Ar cachesize
Specify the size of the memory cache in megabytes used by the
hashing 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
.Nm
in megabytes will be a little bit more than twice the figure
specified here.
If unspecified, this value will be calculated based on the size of
the input file up to a maximum of 8 megabytes.
.It Fl d Ar directory
Change the root directory of the generated files from
.Dq Pa /
to
.Ar directory .
.It Fl L
Store data in little-endian format (see also
.Fl B ) .
.It Fl l
Use
.Xr syslog 3
to report errors.
.It Fl p
Create a Version 7 style password file and install it into
.Dq Pa /etc/passwd .
.It Fl s
Update the secure database only.
This is useful when only encrypted passwords have changed.
This option negates the effect of any
.Fl p
option.
.It Fl u Ar name
Don't re-build the database files, but instead modify or add entries
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 password file.
.It Fl V Ar version
Upgrade or downgrade databases to the numbered version.
Version
.Dv 0
is the old format (up to and including
.Nx 5.0 )
with the 4 byte time fields and version
.Dv 1
is the new format with the 8 byte time fields (greater than
.Nx 5.0 ) .
.Nx 5.0
cannot read version
.Dv 1
databases.
All versions above
.Nx 5.0
can read and write both version
.Dv 0
and version
.Dv 1
databases.
By default the databases stay in the version they were before the command
was run.
.It Fl v
Mention when a version change occurs.
.It Fl w
Print a warning if the system is using old style databases.
.El
.Pp
The two databases differ in that the secure version contains the user's
encrypted password and the insecure version has an asterisk
.Pq Dq * .
.Pp
The databases are used by the C library password routines (see
.Xr getpwent 3 ) .
.Sh FILES
.Bl -tag -width Pa -compact
.It Pa /etc/master.passwd
The current password file.
.It Pa /etc/passwd
A Version 7 format password file.
.It Pa /etc/pwd.db
The insecure password database file.
.It Pa /etc/pwd.db.tmp
A temporary file.
.It Pa /etc/spwd.db
The secure password database file.
.It Pa /etc/spwd.db.tmp
A temporary file.
.El
.Sh EXIT STATUS
.Nm
exits zero on success, non-zero on failure.
.Sh COMPATIBILITY
Previous versions of the system had a program similar to
.Nm
which built
.Em dbm
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.
.Sh SEE ALSO
.Xr chpass 1 ,
.Xr passwd 1 ,
.Xr pwhash 1 ,
.Xr db 3 ,
.Xr getpwent 3 ,
.Xr pw_mkdb 3 ,
.Xr syslog 3 ,
.Xr passwd 5 ,
.Xr useradd 8 ,
.Xr userdel 8 ,
.Xr usermod 8 ,
.Xr vipw 8
.Sh BUGS
Because of the necessity for atomic update of the password files,
.Nm
uses
.Xr rename 2
to install them.
This, however, requires that the file specified on the command line live
on the same file system as the
.Dq Pa /etc
directory.
.Pp
There are the obvious races with multiple people running
.Nm
on different password files at the same time.
The front-ends to
.Xr chpass 1 ,
.Xr passwd 1 ,
.Xr useradd 8 ,
.Xr userdel 8 ,
.Xr usermod 8 ,
and
.Xr vipw 8
handle the locking necessary to avoid this problem.
.Pp
The database files are copied when the
.Fl u
option is used.
Real locking would make this unnecessary.
.Pp
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.
.Pp
Using the
.Fl u
option on a system where multiple users share the same UID can have
unexpected results.