mirror of https://github.com/mkerrisk/man-pages
266 lines
6.6 KiB
Groff
266 lines
6.6 KiB
Groff
.\" 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.
|
|
.\"
|
|
.\" Since the Linux kernel and libraries are constantly changing, this
|
|
.\" manual page may be incorrect or out-of-date. The author(s) assume no
|
|
.\" responsibility for errors or omissions, or for damages resulting from
|
|
.\" the use of the information contained herein. The author(s) may not
|
|
.\" have taken the same level of care in the production of this manual,
|
|
.\" which is licensed free of charge, as they might when working
|
|
.\" professionally.
|
|
.\"
|
|
.\" Formatted or processed versions of this manual, if unaccompanied by
|
|
.\" the source, must acknowledge the copyright and authors of this work.
|
|
.\" %%%LICENSE_END
|
|
.\"
|
|
.\" References consulted:
|
|
.\" Linux libc source code
|
|
.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
|
|
.\" 386BSD man pages
|
|
.\"
|
|
.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
|
|
.\" Modified 2003-11-15 by aeb
|
|
.\"
|
|
.TH GETGRNAM 3 2021-03-22 "" "Linux Programmer's Manual"
|
|
.SH NAME
|
|
getgrnam, getgrnam_r, getgrgid, getgrgid_r \- get group file entry
|
|
.SH SYNOPSIS
|
|
.nf
|
|
.B #include <sys/types.h>
|
|
.B #include <grp.h>
|
|
.PP
|
|
.BI "struct group *getgrnam(const char *" name );
|
|
.BI "struct group *getgrgid(gid_t " gid );
|
|
.PP
|
|
.BI "int getgrnam_r(const char *restrict " name \
|
|
", struct group *restrict " grp ,
|
|
.BI " char *restrict " buf ", size_t " buflen ,
|
|
.BI " struct group **restrict " result );
|
|
.BI "int getgrgid_r(gid_t " gid ", struct group *restrict " grp ,
|
|
.BI " char *restrict " buf ", size_t " buflen ,
|
|
.BI " struct group **restrict " result );
|
|
.fi
|
|
.PP
|
|
.RS -4
|
|
Feature Test Macro Requirements for glibc (see
|
|
.BR feature_test_macros (7)):
|
|
.RE
|
|
.PP
|
|
.BR getgrnam_r (),
|
|
.BR getgrgid_r ():
|
|
.nf
|
|
_POSIX_C_SOURCE
|
|
|| /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
|
|
.fi
|
|
.SH DESCRIPTION
|
|
The
|
|
.BR getgrnam ()
|
|
function returns a pointer to a structure containing
|
|
the broken-out fields of the record in the group database
|
|
(e.g., the local group file
|
|
.IR /etc/group ,
|
|
NIS, and LDAP)
|
|
that matches the group name
|
|
.IR name .
|
|
.PP
|
|
The
|
|
.BR getgrgid ()
|
|
function returns a pointer to a structure containing
|
|
the broken-out fields of the record in the group database
|
|
that matches the group ID
|
|
.IR gid .
|
|
.PP
|
|
The \fIgroup\fP structure is defined in \fI<grp.h>\fP as follows:
|
|
.PP
|
|
.in +4n
|
|
.EX
|
|
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 */
|
|
};
|
|
.EE
|
|
.in
|
|
.PP
|
|
For more information about the fields of this structure, see
|
|
.BR group (5).
|
|
.PP
|
|
The
|
|
.BR getgrnam_r ()
|
|
and
|
|
.BR getgrgid_r ()
|
|
functions obtain the same information as
|
|
.BR getgrnam ()
|
|
and
|
|
.BR getgrgid (),
|
|
but store the retrieved
|
|
.I group
|
|
structure
|
|
in the space pointed to by
|
|
.IR grp .
|
|
The string fields pointed to by the members of the
|
|
.I group
|
|
structure are stored in the buffer
|
|
.I buf
|
|
of size
|
|
.IR buflen .
|
|
A pointer to the result (in case of success) or NULL (in case no entry
|
|
was found or an error occurred) is stored in
|
|
.IR *result .
|
|
.PP
|
|
The call
|
|
.PP
|
|
sysconf(_SC_GETGR_R_SIZE_MAX)
|
|
.PP
|
|
returns either \-1, without changing
|
|
.IR errno ,
|
|
or an initial suggested size for
|
|
.IR buf .
|
|
(If this size is too small,
|
|
the call fails with
|
|
.BR ERANGE ,
|
|
in which case the caller can retry with a larger buffer.)
|
|
.SH RETURN VALUE
|
|
The
|
|
.BR getgrnam ()
|
|
and
|
|
.BR getgrgid ()
|
|
functions return a pointer to a
|
|
.I group
|
|
structure, or NULL if the matching entry
|
|
is not found or an error occurs.
|
|
If an error occurs,
|
|
.I errno
|
|
is set to indicate the error.
|
|
If one wants to check
|
|
.I errno
|
|
after the call, it should be set to zero before the call.
|
|
.PP
|
|
The return value may point to a static area, and may be overwritten
|
|
by subsequent calls to
|
|
.BR getgrent (3),
|
|
.BR getgrgid (),
|
|
or
|
|
.BR getgrnam ().
|
|
(Do not pass the returned pointer to
|
|
.BR free (3).)
|
|
.PP
|
|
On success,
|
|
.BR getgrnam_r ()
|
|
and
|
|
.BR getgrgid_r ()
|
|
return zero, and set
|
|
.IR *result
|
|
to
|
|
.IR grp .
|
|
If no matching group record was found,
|
|
these functions return 0 and store NULL in
|
|
.IR *result .
|
|
In case of error, an error number is returned, and NULL is stored in
|
|
.IR *result .
|
|
.SH ERRORS
|
|
.TP
|
|
.BR 0 " or " ENOENT " or " ESRCH " or " EBADF " or " EPERM " or ..."
|
|
The given
|
|
.I name
|
|
or
|
|
.I gid
|
|
was not found.
|
|
.TP
|
|
.B EINTR
|
|
A signal was caught; see
|
|
.BR signal (7).
|
|
.TP
|
|
.B EIO
|
|
I/O error.
|
|
.TP
|
|
.B EMFILE
|
|
The per-process limit on the number of open file descriptors has been reached.
|
|
.TP
|
|
.B ENFILE
|
|
The system-wide limit on the total number of open files has been reached.
|
|
.TP
|
|
.B ENOMEM
|
|
.\" not in POSIX
|
|
Insufficient memory to allocate
|
|
.I group
|
|
structure.
|
|
.\" to allocate the group structure, or to allocate buffers
|
|
.TP
|
|
.B ERANGE
|
|
Insufficient buffer space supplied.
|
|
.SH FILES
|
|
.TP
|
|
.I /etc/group
|
|
local group database file
|
|
.SH ATTRIBUTES
|
|
For an explanation of the terms used in this section, see
|
|
.BR attributes (7).
|
|
.ad l
|
|
.nh
|
|
.TS
|
|
allbox;
|
|
lb lb lbx
|
|
l l l.
|
|
Interface Attribute Value
|
|
T{
|
|
.BR getgrnam ()
|
|
T} Thread safety T{
|
|
MT-Unsafe race:grnam locale
|
|
T}
|
|
T{
|
|
.BR getgrgid ()
|
|
T} Thread safety T{
|
|
MT-Unsafe race:grgid locale
|
|
T}
|
|
T{
|
|
.BR getgrnam_r (),
|
|
.BR getgrgid_r ()
|
|
T} Thread safety MT-Safe locale
|
|
.TE
|
|
.hy
|
|
.ad
|
|
.sp 1
|
|
.SH CONFORMING TO
|
|
POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
|
|
.SH NOTES
|
|
The formulation given above under "RETURN VALUE" is from POSIX.1.
|
|
.\" POSIX.1-2001, POSIX.1-2008
|
|
It does not call "not found" an error, hence does not specify what value
|
|
.I errno
|
|
might have in this situation.
|
|
But that makes it impossible to recognize
|
|
errors.
|
|
One might argue that according to POSIX
|
|
.I errno
|
|
should be left unchanged if an entry is not found.
|
|
Experiments on various
|
|
UNIX-like systems show that lots of different values occur in this
|
|
situation: 0, ENOENT, EBADF, ESRCH, EWOULDBLOCK, EPERM, and probably others.
|
|
.\" more precisely:
|
|
.\" AIX 5.1 - gives ESRCH
|
|
.\" OSF1 4.0g - gives EWOULDBLOCK
|
|
.\" libc, glibc up to version 2.6, Irix 6.5 - give ENOENT
|
|
.\" glibc since version 2.7 - give 0
|
|
.\" FreeBSD 4.8, OpenBSD 3.2, NetBSD 1.6 - give EPERM
|
|
.\" SunOS 5.8 - gives EBADF
|
|
.\" Tru64 5.1b, HP-UX-11i, SunOS 5.7 - give 0
|
|
.SH SEE ALSO
|
|
.BR endgrent (3),
|
|
.BR fgetgrent (3),
|
|
.BR getgrent (3),
|
|
.BR getpwnam (3),
|
|
.BR setgrent (3),
|
|
.BR group (5)
|