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



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

NNAAMMEE
       endpwent, getpwent, setpwent -- user database functions

SSYYNNOOPPSSIISS
       #include <pwd.h>

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

DDEESSCCRRIIPPTTIIOONN
       These functions shall retrieve information about users.

       The _g_e_t_p_w_e_n_t() 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 ppaasssswwdd structure. If the user
       database is not already open, _g_e_t_p_w_e_n_t() shall open it and return a
       pointer to a ppaasssswwdd structure containing the first entry in the
       database. Thereafter, it shall return a pointer to a ppaasssswwdd 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, _g_e_t_p_w_e_n_t()
       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 _s_e_t_p_w_e_n_t() function shall rewind the user database so that the next
       _g_e_t_p_w_e_n_t() call returns the first entry, allowing repeated searches.

       The _e_n_d_p_w_e_n_t() function shall close the user database.

       The _s_e_t_p_w_e_n_t() and _e_n_d_p_w_e_n_t() functions shall not change the setting of
       _e_r_r_n_o if successful.

       On error, the _s_e_t_p_w_e_n_t() and _e_n_d_p_w_e_n_t() functions shall set _e_r_r_n_o to
       indicate the error.

       Since no value is returned by the _s_e_t_p_w_e_n_t() and _e_n_d_p_w_e_n_t() functions,
       an application wishing to check for error situations should set _e_r_r_n_o
       to 0, then call the function, then check _e_r_r_n_o.

       These functions need not be thread-safe.

RREETTUURRNN VVAALLUUEE
       On successful completion, _g_e_t_p_w_e_n_t() shall return a pointer to a ppaasssswwdd
       structure. On end-of-file, _g_e_t_p_w_e_n_t() shall return a null pointer and
       shall not change the setting of _e_r_r_n_o.  On error, _g_e_t_p_w_e_n_t() shall
       return a null pointer and _e_r_r_n_o shall be set to indicate the 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 _g_e_t_p_w_u_i_d(), _g_e_t_p_w_n_a_m(), or
       _g_e_t_p_w_e_n_t().  The returned pointer, and pointers within the structure,
       might also be invalidated if the calling thread is terminated.

EERRRROORRSS
       These functions may fail if:

       EEIINNTTRR  A signal was caught during the operation.

       EEIIOO    An I/O error has occurred.

       In addition, _g_e_t_p_w_e_n_t() and _s_e_t_p_w_e_n_t() may fail if:

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

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

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
   SSeeaarrcchhiinngg tthhee UUsseerr DDaattaabbaassee
       The following example uses the _g_e_t_p_w_e_n_t() function to get successive
       entries in the user database, returning a pointer to a ppaasssswwdd structure
       that contains information about each user. The call to _e_n_d_p_w_e_n_t()
       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();
           }

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       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
       _g_e_t_p_w_u_i_d() whenever possible because it avoids these dependencies.

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _e_n_d_g_r_e_n_t(), _g_e_t_l_o_g_i_n(), _g_e_t_p_w_n_a_m(), _g_e_t_p_w_u_i_d()

       The Base Definitions volume of POSIX.1-2017, <<ppwwdd..hh>>

CCOOPPYYRRIIGGHHTT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  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.opengroup.org/unix/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                  2017                          ENDPWENT(3)
