getgrent (3)
Leading comments
Copyright 1993 David Metcalfe (david@prism.demon.co.uk) %%%LICENSE_START(VERBATIM) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Sin...
NAME
getgrent, setgrent, endgrent - get group file entrySYNOPSIS
#include <sys/types.h> #include <grp.h> struct group *getgrent(void); void setgrent(void); void endgrent(void);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
setgrent():
-
_SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED ||
/* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
getgrent(), endgrent():
- _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
DESCRIPTION
The getgrent() function returns a pointer to a structure containing the broken-out fields of a record in the group database (e.g., the local group file /etc/group, NIS, and LDAP). The first time getgrent() is called, it returns the first entry; thereafter, it returns successive entries.The setgrent() function rewinds to the beginning of the group database, to allow repeated scans.
The endgrent() function is used to close the group database after all processing has been performed.
The group structure is defined in <grp.h> as follows:
struct group {
char *gr_name; /* group name */
char *gr_passwd; /* group password */
gid_t gr_gid; /* group ID */
char **gr_mem; /* NULL-terminated array of pointers
to names of group members */
};
For more information about the fields of this structure, see group(5).
RETURN VALUE
The getgrent() function returns a pointer to a group structure, or NULL if there are no more entries or an error occurs.
Upon error,
errno
may be set.
If one wants to check
errno
after the call, it should be set to zero before the call.
The return value may point to a static area, and may be overwritten
by subsequent calls to
getgrent(),
getgrgid(3),
or
getgrnam(3).
(Do not pass the returned pointer to
free(3).)
ERRORS
- EAGAIN
- The service was temporarily unavailable; try again later. For NSS backends in glibc this indicates a temporary error talking to the backend. The error may correct itself, retrying later is suggested.
- EINTR
- A signal was caught.
- EIO
- I/O error.
- EMFILE
- The per-process limit on the number of open file descriptors has been reached.
- ENFILE
- The system-wide limit on the total number of open files has been reached.
- ENOENT A necessary input file cannot be found. For NSS backends in glibc this indicates the backend is not correctly configured.
- ENOMEM
- Insufficient memory to allocate group structure.
- ERANGE
- Insufficient buffer space supplied.
FILES
- /etc/group
- local group database file
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).| Interface | Attribute | Value |
| getgrent() | Thread safety |
MT-Unsafe race:grent
race:grentbuf locale |
| setgrent(), endgrent() | Thread safety | MT-Unsafe race:grent locale |
In the above table, grent in race:grent signifies that if any of the functions setgrent(), getgrent(), or endgrent() are used in parallel in different threads of a program, then data races could occur.