| .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
| .\" |
| .\" %%%LICENSE_START(VERBATIM) |
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| .\" 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 |
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| .\" References consulted: |
| .\" Linux libc source code |
| .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) |
| .\" 386BSD man pages |
| .\" Modified Sat Jul 24 19:29:54 1993 by Rik Faith (faith@cs.unc.edu) |
| .TH GETGRENT 3 2016-03-15 "" "Linux Programmer's Manual" |
| .SH NAME |
| getgrent, setgrent, endgrent \- get group file entry |
| .SH SYNOPSIS |
| .nf |
| .B #include <sys/types.h> |
| .B #include <grp.h> |
| .sp |
| .B struct group *getgrent(void); |
| .sp |
| .B void setgrent(void); |
| .sp |
| .B void endgrent(void); |
| .fi |
| .sp |
| .in -4n |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .in |
| .sp |
| .PD 0 |
| .ad l |
| .BR setgrent (): |
| .RS 4 |
| _XOPEN_SOURCE\ >=\ 500 |
| .\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED |
| || /* Glibc since 2.19: */ _DEFAULT_SOURCE |
| || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE |
| .RE |
| .sp |
| .BR getgrent (), |
| .BR endgrent (): |
| .RS 4 |
| _XOPEN_SOURCE\ >=\ 500 |
| .\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED |
| || /* Since glibc 2.12: */ _POSIX_C_SOURCE\ >=\ 200809L |
| || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE |
| .RE |
| .PD |
| .ad b |
| .SH DESCRIPTION |
| The |
| .BR 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 |
| .IR /etc/group , |
| NIS, and LDAP). |
| The first time |
| .BR getgrent () |
| is called, |
| it returns the first entry; thereafter, it returns successive entries. |
| .PP |
| The |
| .BR setgrent () |
| function rewinds to the beginning |
| of the group database, to allow repeated scans. |
| .PP |
| The |
| .BR endgrent () |
| function is used to close the group database |
| after all processing has been performed. |
| .PP |
| The \fIgroup\fP structure is defined in \fI<grp.h>\fP as follows: |
| .sp |
| .in +4n |
| .nf |
| 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 */ |
| }; |
| .fi |
| .in |
| .PP |
| For more information about the fields of this structure, see |
| .BR group (5). |
| .SH RETURN VALUE |
| The |
| .BR getgrent () |
| function returns a pointer to a |
| .I group |
| structure, |
| or NULL if there are no more entries or an error occurs. |
| .LP |
| Upon error, |
| .I errno |
| may be set. |
| If one wants to check |
| .I 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 |
| .BR getgrent (), |
| .BR getgrgid (3), |
| or |
| .BR getgrnam (3). |
| (Do not pass the returned pointer to |
| .BR free (3).) |
| .SH ERRORS |
| .TP |
| .B 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. |
| .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 |
| .\" not in POSIX |
| .B ENOENT |
| A necessary input file cannot be found. |
| For NSS backends in glibc this indicates the backend is not correctly configured. |
| .TP |
| .B ENOMEM |
| .\" not in POSIX |
| Insufficient memory to allocate |
| .I group |
| structure. |
| .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). |
| .TS |
| allbox; |
| lbw11 lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR getgrent () |
| T} Thread safety T{ |
| MT-Unsafe race:grent |
| .br |
| race:grentbuf locale |
| T} |
| T{ |
| .BR setgrent (), |
| .BR endgrent () |
| T} Thread safety MT-Unsafe race:grent locale |
| .TE |
| |
| In the above table, |
| .I grent |
| in |
| .I race:grent |
| signifies that if any of the functions |
| .BR setgrent (), |
| .BR getgrent (), |
| or |
| .BR endgrent () |
| are used in parallel in different threads of a program, |
| then data races could occur. |
| .SH CONFORMING TO |
| POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD. |
| .SH SEE ALSO |
| .BR fgetgrent (3), |
| .BR getgrent_r (3), |
| .BR getgrgid (3), |
| .BR getgrnam (3), |
| .BR getgrouplist (3), |
| .BR putgrent (3), |
| .BR group (5) |