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man:getgrent

GETGRENT(3) Linux Programmer's Manual GETGRENT(3)

NAME

     getgrent, setgrent, endgrent - get group file entry

SYNOPSIS

     #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():
         _XOPEN_SOURCE >= 500
             || /* Glibc since 2.19: */ _DEFAULT_SOURCE
             || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
     getgrent(), endgrent():
         Since glibc 2.22:
             _XOPEN_SOURCE >= 500 ||
                 _DEFAULT_SOURCE
         Glibc 2.21 and earlier
             _XOPEN_SOURCE >= 500
                 || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
                 || /* Glibc versions <= 2.19: */ _BSD_SOURCE ||
         _SVID_SOURCE

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; see signal(7).
     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(), | Thread safety | MT-Unsafe race:grent locale |
     |endgrent()  |               |                             |
     +------------+---------------+-----------------------------+
     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.

CONFORMING TO

     POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.

SEE ALSO

     fgetgrent(3), getgrent_r(3), getgrgid(3), getgrnam(3), getgrouplist(3),
     putgrent(3), group(5)

COLOPHON

     This page is part of release 4.16 of the Linux  man-pages  project.   A
     description  of  the project, information about reporting bugs, and the
     latest    version    of    this    page,    can     be     found     at
     https://www.kernel.org/doc/man-pages/.
                                2017-09-15                       GETGRENT(3)
/data/webs/external/dokuwiki/data/pages/man/getgrent.txt · Last modified: 2019/05/17 09:32 by 127.0.0.1

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