GETGRNAM(3) Linux Programmer's Manual GETGRNAM(3)
NAME
getgrnam, getgrnam_r, getgrgid, getgrgid_r - get group file(1,n) entry
SYNOPSIS
#include <sys/types.h>
#include <grp.h>
struct group *getgrnam(const char *name);
struct group *getgrgid(gid_t gid);
int getgrnam_r(const char *name, struct group *gbuf,
char *buf, size_t buflen, struct group **gbufp);
int getgrgid_r(gid_t gid, struct group *gbuf,
char *buf, size_t buflen, struct group **gbufp);
DESCRIPTION
The getgrnam() function returns a pointer to a structure containing the
group information from /etc/group for the entry that matches the group
name name.
The getgrgid() function returns a pointer to a structure containing the
group information from /etc/group for the entry that matches the group
gid gid.
The getgrnam_r() and getgrgid_r() functions find the same information,
but store the retrieved group structure in(1,8) the space pointed to by
gbuf. This group structure contains pointers to strings, and these
strings are stored in(1,8) the buffer buf of size buflen. A pointer to the
result (in(1,8) case of success) or NULL (in(1,8) case no entry was found or an
error(8,n) occurred) is stored in(1,8) *gbufp.
The group structure is defined in(1,8) <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; /* group members */
};
The maximum needed size for buf can be found using sysconf(3) with the
_SC_GETGR_R_SIZE_MAX parameter.
RETURN VALUE
The getgrnam() and getgrgid() functions return a pointer to the group
information structure, or NULL if(3,n) the matching entry is not found or an
error(8,n) occurs. If an error(8,n) occurs, errno is set(7,n,1 builtins) appropriately. If one
wants to check errno after the call, it should be set(7,n,1 builtins) to zero before
the call.
The return value may point to static area, and may be overwritten by
subsequent calls to getgrent(), getgrgid(), or getgrnam().
The getgrnam_r() and getgrgid_r() functions return zero on success. In
case of error(8,n), an error(8,n) value is returned.
ERRORS
0 or ENOENT or ESRCH or EBADF or EPERM or ...
The given name or gid was not found.
EINTR A signal(2,7) was caught.
EIO I/O error.
EMFILE The maximum number (OPEN_MAX) of files was open(2,3,n) already in(1,8) the
calling process.
ENFILE The maximum number of files was open(2,3,n) already in(1,8) the system.
ENOMEM Insufficient memory.
ERANGE Insufficient buffer space supplied.
FILES
/etc/group
group database file(1,n)
CONFORMING TO
SVID 3, BSD 4.3, POSIX 1003.1-2003
NOTES
The formulation given above under "RETURN VALUE" is from POSIX
1003.1-2001. It does not call "not found" an error(8,n), hence does not
specify what value errno might have in(1,8) this situation. But that makes
it impossible to recognize errors. One might argue that according to
POSIX errno should be left unchanged if(3,n) an entry is not found. Experi-
ments on various Unix-like systems shows that lots of different values
occur in(1,8) this situation: 0, ENOENT, EBADF, ESRCH, EWOULDBLOCK, EPERM
and probably others.
SEE ALSO
endgrent(3), fgetgrent(3), getgrent(3), getpwnam(3), setgrent(3),
group(5)
2003-11-15 GETGRNAM(3)