GETPWENT(3) BSD Programmer's Manual GETPWENT(3)
getpwent, getpwnam, getpwuid, setpassent, setpwent, endpwent - password
database operations
#include <sys/types.h>
#include <pwd.h>
struct passwd *
getpwent(void);
struct passwd *
getpwnam(const char *login);
struct passwd *
getpwuid(uid_t uid);
int
setpassent(int stayopen);
void
setpwent(void);
void
endpwent(void);
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 functions getpwnam() and getpwuid() search the password database for
the given login name or user ID, respectively, always returning the first
one encountered.
getpwent() sequentially reads the password database and is intended for
programs that wish to process the complete list of users.
setpassent() accomplishes two purposes. First, it causes getpwent() to
"rewind" to the beginning of the database. Additionally, if stayopen is
non-zero, file descriptors are left open, significantly speeding up sub-
sequent accesses for all of the routines. (This latter functionality is
unnecessary for getpwent() as it doesn't close its file descriptors by
default.)
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open as the database will become out of date if it is updated while the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.
setpwent() is equivalent to setpassent() with an argument of zero.
The endpwent() function closes any open files.
These routines have been written to "shadow" the password file, i.e., al-
low 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 re-
turned, otherwise, the password field of the returned structure will
point to the string '*'.
The functions getpwent(), getpwnam(), and getpwuid() return a valid
pointer to a passwd structure on success or a null pointer if end-of-file
is reached or an error occurs. The setpassent() function returns 0 on
failure or 1 on success. The endpwent() and setpwent() functions have no
return value.
/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
getlogin(2), getgrent(3), pw_dup(3), passwd(5), pwd_mkdb(8), vipw(8)
The getpwent(), getpwnam(), getpwuid(), setpwent(), and endpwent() func-
tions appeared in Version 7 AT&T UNIX. The setpassent() function appeared
in 4.3BSD-Reno.
The historic function setpwfile(3), which allowed the specification of
alternate password databases, has been deprecated and is no longer avail-
able.
The functions getpwent(), getpwnam(), and getpwuid() leave their results
in an internal static object and return a pointer to that object. Subse-
quent calls to any of these functions will modify the same object.
The routines getpwent(), endpwent(), setpassent(), and setpwent() are
fairly useless in a networked environment and should be avoided, if pos-
sible.
MirBSD #10-current December 11, 1993 1