GETPWENT(3) Linux Programmer's Manual GETPWENT(3)
NAME
getpwent, setpwent, endpwent - get password file entry
SYNOPSIS
#include <sys/types.h>
#include <pwd.h>
struct passwd *getpwent(void);
void setpwent(void);
void endpwent(void);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
getpwent(), setpwent(), endpwent():
_XOPEN_SOURCE >= 500
|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
DESCRIPTION
The getpwent() function returns a pointer to a structure containing the
broken-out fields of a record from the password database (e.g., the lo-
cal password file /etc/passwd, NIS, and LDAP). The first time getp-
went() is called, it returns the first entry; thereafter, it returns
successive entries.
The setpwent() function rewinds to the beginning of the password data-
base.
The endpwent() function is used to close the password database after
all processing has been performed.
The passwd structure is defined in <pwd.h> as follows:
struct passwd {
char *pw_name; /* username */
char *pw_passwd; /* user password */
uid_t pw_uid; /* user ID */
gid_t pw_gid; /* group ID */
char *pw_gecos; /* user information */
char *pw_dir; /* home directory */
char *pw_shell; /* shell program */
};
When shadow(5) passwords are enabled (which is default on many
GNU/Linux installations) the content of pw_passwd is usually not very
useful. In such a case most passwords are stored in a separate file.
The variable pw_shell may be empty, in which case the system will exe-
cute the default shell (/bin/sh) for the user.
For more information about the fields of this structure, see passwd(5).
RETURN VALUE
The getpwent() function returns a pointer to a passwd structure, or
NULL if there are no more entries or an error occurred. If an error
occurs, errno is set appropriately. 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 getpwent(), getpwnam(3), or getpwuid(3). (Do not
pass the returned pointer to free(3).)
ERRORS
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.
ENOMEM Insufficient memory to allocate passwd structure.
ERANGE Insufficient buffer space supplied.
FILES
/etc/passwd
local password database file
ATTRIBUTES
For an explanation of the terms used in this section, see at-
tributes(7).
+------------+---------------+-----------------------------+
|Interface | Attribute | Value |
+------------+---------------+-----------------------------+
|getpwent() | Thread safety | MT-Unsafe race:pwent |
| | | race:pwentbuf locale |
+------------+---------------+-----------------------------+
|setpwent(), | Thread safety | MT-Unsafe race:pwent locale |
|endpwent() | | |
+------------+---------------+-----------------------------+
In the above table, pwent in race:pwent signifies that if any of the
functions setpwent(), getpwent(), or endpwent() 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. The pw_gecos field is not
specified in POSIX, but is present on most implementations.
SEE ALSO
fgetpwent(3), getpw(3), getpwent_r(3), getpwnam(3), getpwuid(3), putp-
went(3), shadow(5), passwd(5)
COLOPHON
This page is part of release 5.07 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/.
GNU 2017-09-15 GETPWENT(3)