| GETPWENT(3) |
AerieBSD 1.0 Refernce Manual |
GETPWENT(3) |
NAME
getpwent —
setpwent,
endpwent
sequential password database access
SYNOPSIS
#include <sys/types.h>
#include <pwd.h>
structpasswd *
getpwent(void);
void
setpwent(void);
void
endpwent(void);
DESCRIPTION
These functions operate on the password database file which is described in
passwd(5).
Each entry in the database is defined by the structure
struct passwd
found in the include file
‹pwd.h›:
struct passwd {
char *pw_name; /* user name */
char *pw_passwd; /* encrypted password */
uid_t pw_uid; /* user uid */
gid_t pw_gid; /* user gid */
time_t pw_change; /* password change time */
char *pw_class; /* user access class */
char *pw_gecos; /* Honeywell login info */
char *pw_dir; /* home directory */
char *pw_shell; /* default shell */
time_t pw_expire; /* account expiration */
};
The
getpwent();
function sequentially reads the password database and is intended for programs
that wish to process the complete list of users.
It is dangerous for long-running programs to keep the file descriptors
open as the database will become out of date if it is updated while the
program is running.
Furthermore, programs that run child processes should be careful to call
endpwent();
to close these descriptors before calling
execve(2)
or
system(3).
setpwent();
causes
getpwent();
to
“rewind”
to the beginning of the database.
The
endpwent();
function closes any file descriptors opened by
setpwent();
or
getpwent();.
These routines have been written to
“shadow”
the password file, that is,
allow only certain programs to have access to the encrypted password.
If the process which calls them has an effective UID of 0 or has the
“_shadow”
group in its group vector, the encrypted password will be returned, otherwise,
the password field of the returned structure will point to the string
"*".
YP SUPPORT
If YP is active,
getpwent();
also uses the
master.passwd.byname
YP map (if available) or the
passwd.byname
YP map.
This is in addition to the passwd file,
and respects the order of both normal and YP
entries in the passwd file.
RETURN VALUES
The
getpwent();
function returns a valid pointer to a passwd structure on success
or a null pointer if end-of-file is reached or an error occurs.
The
endpwent();
and
setpwent();
functions have no return value.
FILES
- /etc/pwd.db
-
insecure password database file
- /etc/spwd.db
-
secure password database file
- /etc/master.passwd
-
current password file
- /etc/passwd
-
a Version 7 format password file
SEE ALSO
getlogin(2),
getgrent(3),
getgrouplist(3),
getpwnam(3),
pw_dup(3),
passwd(5),
Makefile.yp(8),
pwd_mkdb(8),
vipw(8),
yp(8)
HISTORY
The
getpwent();,
setpwent();,
and
endpwent();
functions appeared in
Version 7 AT&T UNIX.
The historic function
setpwfile(3),
which allowed the specification of alternate password databases,
has been deprecated and is no longer available.
BUGS
The
getpwent();
function stores its results in an internal static buffer and returns
a pointer to that buffer.
Subsequent calls to
getpwent();,
getpwnam();,
or
getpwuid();
will overwrite the same buffer.
The routines
getpwent();,
endpwent();,
and
setpwent();
are fairly useless in a networked environment and should be
avoided, if possible.
| AerieBSD 1.0 Reference Manual |
May 14 2010 |
GETPWENT(3) |