mirror of https://github.com/mkerrisk/man-pages
202 lines
5.2 KiB
Groff
202 lines
5.2 KiB
Groff
.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\"
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.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
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.\" Modified 2003-11-15 by aeb
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.\"
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.TH GETGRNAM 3 2003-11-15 "" "Linux Programmer's Manual"
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.SH NAME
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getgrnam, getgrnam_r, getgrgid, getgrgid_r \- get group file entry
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.SH SYNOPSIS
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.nf
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.B #include <sys/types.h>
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.B #include <grp.h>
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.sp
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.BI "struct group *getgrnam(const char *" name );
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.sp
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.BI "struct group *getgrgid(gid_t " gid );
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.sp
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.BI "int getgrnam_r(const char *" name ", struct group *" gbuf ,
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.br
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.BI " char *" buf ", size_t " buflen ", struct group **" gbufp );
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.sp
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.BI "int getgrgid_r(gid_t " gid ", struct group *" gbuf ,
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.br
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.BI " char *" buf ", size_t " buflen ", struct group **" gbufp );
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.fi
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.SH DESCRIPTION
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The
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.BR getgrnam ()
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function returns a pointer to a structure containing
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the broken-out fields of the record in the group database
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(e.g., the local group file
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.IR /etc/group ,
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NIS, and LDAP)
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that matches the group name
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.IR name .
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.PP
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The
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.BR getgrgid ()
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function returns a pointer to a structure containing
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the broken-out fields of the record in the group database
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that matches the group ID
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.IR gid .
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.PP
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The
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.BR getgrnam_r ()
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and
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.BR getgrgid_r ()
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functions obtain the same information, but store the retrieved
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.I group
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structure
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in the space pointed to by
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.IR gbuf .
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This
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.I group
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structure contains pointers to strings, and these strings
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are stored in the buffer
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.I buf
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of size
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.IR buflen .
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A pointer to the result (in case of success) or NULL (in case no entry
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was found or an error occurred) is stored in
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.IR *gbufp .
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.PP
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The \fIgroup\fP structure is defined in \fI<grp.h>\fP as follows:
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.sp
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.in +4n
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.nf
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struct group {
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char *gr_name; /* group name */
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char *gr_passwd; /* group password */
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gid_t gr_gid; /* group ID */
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char **gr_mem; /* group members */
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};
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.fi
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.in
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.PP
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The maximum needed size for
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.I buf
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can be found using
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.BR sysconf (3)
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with the
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.B _SC_GETGR_R_SIZE_MAX
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parameter.
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.SH "RETURN VALUE"
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The
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.BR getgrnam ()
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and
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.BR getgrgid ()
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functions return a pointer to a
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.I group
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structure, or NULL if the matching entry
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is not found or an error occurs.
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If an error occurs,
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.I errno
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is set appropriately.
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If one wants to check
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.I errno
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after the call, it should be set to zero before the call.
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.LP
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The return value may point to static area, and may be overwritten
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by subsequent calls to
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.BR getgrent (3),
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.BR getgrgid (),
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or
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.BR getgrnam ().
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.LP
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The
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.BR getgrnam_r ()
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and
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.BR getgrgid_r ()
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functions return
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zero on success.
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In case of error, an error number is returned.
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.SH ERRORS
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.TP
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.BR 0 " or " ENOENT " or " ESRCH " or " EBADF " or " EPERM " or ... "
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The given
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.I name
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or
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.I gid
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was not found.
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.TP
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.B EINTR
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A signal was caught.
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.TP
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.B EIO
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I/O error.
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.TP
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.B EMFILE
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The maximum number
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.RB ( OPEN_MAX )
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of files was open already in the calling process.
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.TP
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.B ENFILE
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The maximum number of files was open already in the system.
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.TP
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.B ENOMEM
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.\" not in POSIX
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Insufficient memory to allocate group structure.
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.\" to allocate the group structure, or to allocate buffers
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.TP
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.B ERANGE
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Insufficient buffer space supplied.
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.SH FILES
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.TP
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.I /etc/group
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local group database file
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.SH "CONFORMING TO"
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SVr4, 4.3BSD, POSIX.1-2001
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.SH NOTES
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The formulation given above under "RETURN VALUE" is from POSIX.1-2001.
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It does not call "not found" an error, hence does not specify what value
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.I errno
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might have in this situation.
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But that makes it impossible to recognize
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errors.
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One might argue that according to POSIX
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.I errno
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should be left unchanged if an entry is not found.
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Experiments on various
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Unix-like systems shows that lots of different values occur in this
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situation: 0, ENOENT, EBADF, ESRCH, EWOULDBLOCK, EPERM and probably others.
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.\" more precisely:
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.\" AIX 5.1 - gives ESRCH
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.\" OSF1 4.0g - gives EWOULDBLOCK
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.\" libc, glibc, Irix 6.5 - give ENOENT
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.\" FreeBSD 4.8, OpenBSD 3.2, NetBSD 1.6 - give EPERM
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.\" SunOS 5.8 - gives EBADF
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.\" Tru64 5.1b, HP-UX-11i, SunOS 5.7 - give 0
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.SH "SEE ALSO"
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.BR endgrent (3),
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.BR fgetgrent (3),
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.BR getgrent (3),
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.BR getpwnam (3),
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.BR setgrent (3),
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.BR group (5)
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