PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

ENDPWENT(3P)              POSIX Programmer's Manual             ENDPWENT(3P)

PROLOG         top

       This manual page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior), or
       the interface may not be implemented on Linux.

NAME         top

       endpwent, getpwent, setpwent — user database functions

SYNOPSIS         top

       #include <pwd.h>

       void endpwent(void);
       struct passwd *getpwent(void);
       void setpwent(void);

DESCRIPTION         top

       These functions shall retrieve information about users.

       The getpwent() function shall return a pointer to a structure
       containing the broken-out fields of an entry in the user database.
       Each entry in the user database contains a passwd structure. When
       first called, getpwent() shall return a pointer to a passwd structure
       containing the first entry in the user database. Thereafter, it shall
       return a pointer to a passwd structure containing the next entry in
       the user database. Successive calls can be used to search the entire
       user database.

       If an end-of-file or an error is encountered on reading, getpwent()
       shall return a null pointer.

       An implementation that provides extended security controls may impose
       further implementation-defined restrictions on accessing the user
       database. In particular, the system may deny the existence of some or
       all of the user database entries associated with users other than the
       caller.

       The setpwent() function effectively rewinds the user database to
       allow repeated searches.

       The endpwent() function may be called to close the user database when
       processing is complete.

       These functions need not be thread-safe.

RETURN VALUE         top

       The getpwent() function shall return a null pointer on end-of-file or
       error.

       The application shall not modify the structure to which the return
       value points, nor any storage areas pointed to by pointers within the
       structure. The returned pointer, and pointers within the structure,
       might be invalidated or the structure or the storage areas might be
       overwritten by a subsequent call to getpwuid(), getpwnam(), or
       getpwent().

ERRORS         top

       These functions may fail if:

       EIO    An I/O error has occurred.

       In addition, getpwent() and setpwent() may fail if:

       EMFILE All file descriptors available to the process are currently
              open.

       ENFILE The maximum allowable number of files is currently open in the
              system.

       The following sections are informative.

EXAMPLES         top

   Searching the User Database
       The following example uses the getpwent() function to get successive
       entries in the user database, returning a pointer to a passwd
       structure that contains information about each user. The call to
       endpwent() closes the user database and cleans up.

           #include <pwd.h>
           #include <stdio.h>

           void printname(uid_t uid)
           {
               struct passwd *pwd;

               setpwent();
               while((pwd = getpwent()) != NULL) {
                   if (pwd->pw_uid == uid) {
                       printf("name=%s\n",pwd->pw_name);
                       break;
                   }
               }
               endpwent();
           }

APPLICATION USAGE         top

       These functions are provided due to their historical usage.
       Applications should avoid dependencies on fields in the password
       database, whether the database is a single file, or where in the file
       system name space the database resides. Applications should use
       getpwuid() whenever possible because it avoids these dependencies.

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       endgrent(3p), getlogin(3p), getpwnam(3p), getpwuid(3p)

       The Base Definitions volume of POSIX.1‐2008, pwd.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) In the event of any discrepancy between this version and
       the original IEEE and The Open Group Standard, the original IEEE and
       The Open Group Standard is the referee document. The original
       Standard can be obtained online at http://www.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the
       source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                 2013                        ENDPWENT(3P)

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