1user_from_uid(3)         BSD Library Functions Manual         user_from_uid(3)
2

NAME

4     user_from_uid, uid_from_user, group_from_gid, gid_from_group — cache
5     password and group entries
6

LIBRARY

8     Utility functions from BSD systems (libbsd, -lbsd)
9

SYNOPSIS

11     #include <pwd.h>
12     (See libbsd(7) for include usage.)
13
14     int
15     uid_from_user(const char *name, uid_t *uid);
16
17     const char *
18     user_from_uid(uid_t uid, int nouser);
19
20     #include <grp.h>
21
22     int
23     gid_from_group(const char *name, gid_t *gid);
24
25     const char *
26     group_from_gid(gid_t gid, int nogroup);
27

DESCRIPTION

29     The user_from_uid() function returns the user name associated with the
30     argument uid.  The user name is cached so that multiple calls with the
31     same uid do not require additional calls to getpwuid(3).  If there is no
32     user associated with the uid, a pointer is returned to a string represen‐
33     tation of the uid, unless the argument nouser is non-zero, in which case
34     a null pointer is returned.
35
36     The uid_from_user() function returns the user ID associated with the ar‐
37     gument name.  The user ID is cached so that multiple calls with the same
38     name do not require additional calls to getpwnam(3).  If there is no user
39     ID associated with the name, the uid_from_user() function returns -1;
40     otherwise it stores the user ID at the location pointed to by uid and re‐
41     turns 0.
42
43     The group_from_gid() function returns the group name associated with the
44     argument gid.  The group name is cached so that multiple calls with the
45     same gid do not require additional calls to getgrgid(3).  If there is no
46     group associated with the gid, a pointer is returned to a string repre‐
47     sentation of the gid, unless the argument nogroup is non-zero, in which
48     case a null pointer is returned.
49
50     The gid_from_group() function returns the group ID associated with the
51     argument name.  The group ID is cached so that multiple calls with the
52     same name do not require additional calls to getgrnam(3).  If there is no
53     group ID associated with the name, the gid_from_group() function returns
54     -1; otherwise it stores the group ID at the location pointed to by gid
55     and returns 0.
56

SEE ALSO

58     getgrgid(3), getpwuid(3)
59

HISTORY

61     The user_from_uid() and group_from_gid() functions first appeared in
62     4.4BSD.
63
64     The uid_from_user() and gid_from_group() functions were ported from
65     NetBSD and first appeared in OpenBSD 6.4.
66
67BSD                           September 13, 2018                           BSD