getpwent

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
       local  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
       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
       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 4.15 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)
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