shadow/man/shadow.3

.\" $Id: shadow.3,v 1.13 2005/04/12 16:31:06 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 int		sp_lstchg; /* last password change */
.br
	long int		sp_min; /* days until change allowed. */
.br
	long int		sp_max; /* days before change required */
.br
	long int		sp_warn; /* days warning for expiration */
.br
	long int		sp_inact; /* days before account inactive */
.br
	long int		sp_expire; /* date when account expires */
.br
	unsigned long 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
\fI/etc/shadow\fR	\- secure user account information
.SH SEE ALSO
.BR getpwent (3),
.BR shadow (5)
.SH AUTHOR
Julianne Frances Haugh (jockgrrl@ix.netcom.com)