getpwent(3) - Linux manual page (original) (raw)

getpwent(3) Library Functions Manual getpwent(3)

NAME top

   getpwent, setpwent, endpwent - get password file entry

LIBRARY top

   Standard C library (_libc_, _-lc_)

SYNOPSIS top

   **#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 >= 2.19: */ _DEFAULT_SOURCE
           || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION top

   The **getpwent**() function returns a pointer to a structure
   containing the broken-out fields of a record from the password
   database (e.g., the local password file _/etc/passwd_, NIS, and
   LDAP).  The first time **getpwent**() is called, it returns the first
   entry; thereafter, it returns successive entries.

   The **setpwent**() function rewinds to the beginning of the password
   database.

   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 */
       };

   For more information about the fields of this structure, see
   [passwd(5)](../man5/passwd.5.html).

RETURN VALUE top

   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](../man3/errno.3.html)_ is set to indicate the error.  If one wants to
   check _[errno](../man3/errno.3.html)_ 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)](../man3/getpwnam.3.html), or
   [getpwuid(3)](../man3/getpwuid.3.html).  (Do not pass the returned pointer to [free(3)](../man3/free.3.html).)

ERRORS top

   **EINTR** A signal was caught; see [signal(7)](../man7/signal.7.html).

   **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 top

   _/etc/passwd_
          local password database file

ATTRIBUTES top

   For an explanation of the terms used in this section, see
   [attributes(7)](../man7/attributes.7.html).
   ┌─────────────┬───────────────┬──────────────────────────────────┐
   │ **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.

VERSIONS top

   The _pwgecos_ field is not specified in POSIX, but is present on
   most implementations.

STANDARDS top

   POSIX.1-2008.

HISTORY top

   POSIX.1-2001, SVr4, 4.3BSD.

SEE ALSO top

   [fgetpwent(3)](../man3/fgetpwent.3.html), [getpw(3)](../man3/getpw.3.html), [getpwent_r(3)](../man3/getpwent%5Fr.3.html), [getpwnam(3)](../man3/getpwnam.3.html), [getpwuid(3)](../man3/getpwuid.3.html),
   [putpwent(3)](../man3/putpwent.3.html), [passwd(5)](../man5/passwd.5.html)

COLOPHON top

   This page is part of the _man-pages_ (Linux kernel and C library
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   man-pages@man7.org

Linux man-pages 6.10 2024-07-23 getpwent(3)

Pages that refer to this page:getent(1), pmcd(1), pmdapipe(1), fgetpwent(3), getpw(3), getpwent_r(3), getpwnam(3), getspnam(3), getspnam(3@@shadow-utils), putpwent(3), setaliasent(3), shadow(3), nss(5), nsswitch.conf(5), passwd(5), genhomedircon(8)