shadow/man/shadow.3

.\"$Id: shadow.3,v 1.7 2001/01/25 10:43:51 kloczek Exp $
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.TH SHADOW 3
.SH NAME
shadow \- encrypted password file routines
.SH SYNTAX
.B #include <shadow.h>
.PP
.B struct spwd *getspent();
.PP
.B struct spwd *getspnam(char
.IB *name );
.PP
.B void setspent();
.PP
.B void endspent();
.PP
.B struct spwd *fgetspent(FILE
.IB *fp );
.PP
.B struct spwd *sgetspent(char
.IB *cp );
.PP
.B int putspent(struct spwd
.I *p,
.B FILE
.IB *fp );
.PP
.B int lckpwdf();
.PP
.B int ulckpwdf();
.SH DESCRIPTION
.I shadow
manipulates the contents of the shadow password file,
\fI/etc/shadow\fR.
The structure in the \fI#include\fR file is
.sp
struct spwd {
.in +.5i
.br
	char	*sp_namp; /* user login name */
.br
	char	*sp_pwdp; /* encrypted password */
.br
	long	sp_lstchg; /* last password change */
.br
	int	sp_min; /* days until change allowed. */
.br
	int	sp_max; /* days before change required */
.br
	int	sp_warn; /* days warning for expiration */
.br
	int	sp_inact; /* days before account inactive */
.br
	int	sp_expire; /* date when account expires */
.br
	int	sp_flag; /* reserved for future use */
.br
.in -.5i
}
.PP
The meanings of each field are
.sp
sp_namp \- pointer to null-terminated user name.
.br
sp_pwdp \- pointer to null-terminated password.
.br
sp_lstchg \- days since Jan 1, 1970 password was last changed.
.br
sp_min \- days before which password may not be changed.
.br
sp_max \- days after which password must be changed.
.br
sp_warn \- days before password is to expire that user is warned
of pending password expiration.
.br
sp_inact \- days after password expires that account is considered
inactive and disabled.
.br
sp_expire \- days since Jan 1, 1970 when account will be disabled.
.br
sp_flag \- reserved for future use.
.SH DESCRIPTION
\fBgetspent\fR, \fBgetspname\fR, \fBfgetspent\fR, and \fBsgetspent\fR
each return a pointer to a \fBstruct spwd\fR.
\fBgetspent\fR returns the
next entry from the file, and \fBfgetspent\fR returns the next
entry from the given stream, which is assumed to be a file of
the proper format.
\fBsgetspent\fR returns a pointer to a \fBstruct spwd\fR using the
provided string as input.
\fBgetspnam\fR searches from the current position in the file for
an entry matching \fBname\fR.
.PP
\fBsetspent\fR and \fBendspent\fR may be used to begin and end,
respectively, access to the shadow password file.
.PP
The \fBlckpwdf\fR and \fBulckpwdf\fR routines should be used to
insure exclusive access to the \fI/etc/shadow\fR file.
\fBlckpwdf\fR attempts to acquire a lock using \fBpw_lock\fR for
up to 15 seconds.
It continues by attempting to acquire a second lock using \fBspw_lock\fR
for the remainder of the initial 15 seconds.
Should either attempt fail after a total of 15 seconds, \fBlckpwdf\fR
returns -1.
When both locks are acquired 0 is returned.
.SH DIAGNOSTICS
Routines return NULL if no more entries are available or if an
error occurs during processing.
Routines which have \fBint\fR as the return value return 0 for
success and -1 for failure.
.SH CAVEATS
These routines may only be used by the super user as access to
the shadow password file is restricted.
.SH FILES
/etc/shadow \- encrypted user passwords
.SH SEE ALSO
.BR getpwent (3),
.BR shadow (5)
.SH AUTHOR
Julianne Frances Haugh (jockgrrl@ix.netcom.com)