getpwent(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | FILES | ATTRIBUTES | CONFORMING TO | SEE ALSO | COLOPHON

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

NAME         top

       getpwent, setpwent, endpwent - get password file entry

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 since 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).

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 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         top

       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         top

       /etc/passwd
              local password database file

ATTRIBUTES         top

       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.

CONFORMING TO         top

       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         top

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

COLOPHON         top

       This page is part of release 5.13 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                            2021-03-22                    GETPWENT(3)

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