user_from_uid(3) BSD Library Functions Manual user_from_uid(3)
NAME
user_from_uid, uid_from_user, group_from_gid, gid_from_group — cache
password and group entries
LIBRARY
Utility functions from BSD systems (libbsd, -lbsd)
SYNOPSIS
#include <pwd.h>
(See libbsd(7) for include usage.)
int
uid_from_user(const char *name, uid_t *uid);
const char *
user_from_uid(uid_t uid, int nouser);
#include <grp.h>
int
gid_from_group(const char *name, gid_t *gid);
const char *
group_from_gid(gid_t gid, int nogroup);
DESCRIPTION
The user_from_uid() function returns the user name associated with the
argument uid. The user name is cached so that multiple calls with the
same uid do not require additional calls to getpwuid(3). If there is no
user associated with the uid, a pointer is returned to a string represen-
tation of the uid, unless the argument nouser is non-zero, in which case
a null pointer is returned.
The uid_from_user() function returns the user ID associated with the ar-
gument name. The user ID is cached so that multiple calls with the same
name do not require additional calls to getpwnam(3). If there is no user
ID associated with the name, the uid_from_user() function returns -1;
otherwise it stores the user ID at the location pointed to by uid and re-
turns 0.
The group_from_gid() function returns the group name associated with the
argument gid. The group name is cached so that multiple calls with the
same gid do not require additional calls to getgrgid(3). If there is no
group associated with the gid, a pointer is returned to a string repre-
sentation of the gid, unless the argument nogroup is non-zero, in which
case a null pointer is returned.
The gid_from_group() function returns the group ID associated with the
argument name. The group ID is cached so that multiple calls with the
same name do not require additional calls to getgrnam(3). If there is no
group ID associated with the name, the gid_from_group() function returns
-1; otherwise it stores the group ID at the location pointed to by gid
and returns 0.
SEE ALSO
getgrgid(3), getpwuid(3)
HISTORY
The user_from_uid() and group_from_gid() functions first appeared in
4.4BSD.
The uid_from_user() and gid_from_group() functions were ported from
NetBSD and first appeared in OpenBSD 6.4.
BSD September 13, 2018 BSD
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