1GETGRNAM(3) Linux Programmer's Manual GETGRNAM(3)
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6 getgrnam, getgrnam_r, getgrgid, getgrgid_r - get group file entry
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9 #include <sys/types.h>
10 #include <grp.h>
11 struct group *getgrnam(const char *name);
13 struct group *getgrgid(gid_t gid);
15 int getgrnam_r(const char *name, struct group *grp,
17 char *buf, size_t buflen, struct group **result);
18 int getgrgid_r(gid_t gid, struct group *grp,
20 char *buf, size_t buflen, struct group **result);
21 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
23 getgrnam_r(), getgrgid_r(): _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE ||
25 _BSD_SOURCE || _SVID_SOURCE || _POSIX_SOURCE
26
28 The getgrnam() function returns a pointer to a structure containing the
29 broken-out fields of the record in the group database (e.g., the local
30 group file /etc/group, NIS, and LDAP) that matches the group name name.
31 The getgrgid() function returns a pointer to a structure containing the
33 broken-out fields of the record in the group database that matches the
34 group ID gid.
35 The getgrnam_r() and getgrgid_r() functions obtain the same informa‐
37 tion, but store the retrieved group structure in the space pointed to
38 by grp. This group structure contains pointers to strings, and these
39 strings are stored in the buffer buf of size buflen. A pointer to the
40 result (in case of success) or NULL (in case no entry was found or an
41 error occurred) is stored in *result.
42 The group structure is defined in <grp.h> as follows:
44 struct group {
46 char *gr_name; /* group name */
47 char *gr_passwd; /* group password */
48 gid_t gr_gid; /* group ID */
49 char **gr_mem; /* group members */
50 };
51 The maximum needed size for buf can be found using sysconf(3) with the
53 argument _SC_GETGR_R_SIZE_MAX.
54
56 The getgrnam() and getgrgid() functions return a pointer to a group
57 structure, or NULL if the matching entry is not found or an error
58 occurs. If an error occurs, errno is set appropriately. If one wants
59 to check errno after the call, it should be set to zero before the
60 call.
61 The return value may point to a static area, and may be overwritten by
63 subsequent calls to getgrent(3), getgrgid(), or getgrnam(). (Do not
64 pass the returned pointer to free(3).)
65 On success, getgrnam_r() and getgrgid_r() return zero, and set *result
67 to grp. If no matching group record was found, these functions return
68 0 and store NULL in *result. In case of error, an error number is
69 returned, and NULL is stored in *result.
70
72 0 or ENOENT or ESRCH or EBADF or EPERM or ...
73 The given name or gid was not found.
74 EINTR A signal was caught.
76 EIO I/O error.
78 EMFILE The maximum number (OPEN_MAX) of files was open already in the
80 calling process.
81 ENFILE The maximum number of files was open already in the system.
83 ENOMEM Insufficient memory to allocate group structure.
85 ERANGE Insufficient buffer space supplied.
87
89 /etc/group
90 local group database file
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93 SVr4, 4.3BSD, POSIX.1-2001.
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96 The formulation given above under "RETURN VALUE" is from POSIX.1-2001.
97 It does not call "not found" an error, hence does not specify what
98 value errno might have in this situation. But that makes it impossible
99 to recognize errors. One might argue that according to POSIX errno
100 should be left unchanged if an entry is not found. Experiments on var‐
101 ious Unix-like systems shows that lots of different values occur in
102 this situation: 0, ENOENT, EBADF, ESRCH, EWOULDBLOCK, EPERM and proba‐
103 bly others.
104
106 endgrent(3), fgetgrent(3), getgrent(3), getpwnam(3), setgrent(3),
107 group(5)
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110 This page is part of release 3.22 of the Linux man-pages project. A
111 description of the project, and information about reporting bugs, can
112 be found at http://www.kernel.org/doc/man-pages/.
113 2009-03-30 GETGRNAM(3)