getpwent(3)                Library Functions Manual                getpwent(3)

NAME
       getpwent, setpwent, endpwent - get password file entry

LIBRARY
       Standard C library (libc, -lc)

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 >= 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 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
       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).

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 to indicate the error.  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
       attributes(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.

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

STANDARDS
       POSIX.1-2008.

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

SEE ALSO
       fgetpwent(3), getpw(3), getpwent_r(3), getpwnam(3), getpwuid(3),
       putpwent(3), passwd(5)

Linux man-pages 6.7               2023-10-31                       getpwent(3)