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



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

NAME
       getpwnam, getpwnam_r - search user database for a name

SYNOPSIS
       #include <pwd.h>

       struct passwd *getpwnam(const char *name);


       int getpwnam_r(const char *name, struct passwd *pwd, char *buffer,
              size_t bufsize, struct passwd **result);


DESCRIPTION
       The getpwnam() function shall search the user database for an entry with a matching name.

       The  getpwnam() function need not be reentrant. A function that is not required to be reentrant is not required
       to be thread-safe.

       Applications wishing to check for error situations should set errno to 0 before calling getpwnam().  If  getpw-
       nam() returns a null pointer and errno is non-zero, an error occurred.

       The  getpwnam_r()  function  shall  update  the  passwd structure pointed to by pwd and store a pointer to that
       structure at the location pointed to by result. The structure shall contain an entry  from  the  user  database
       with a matching name. Storage referenced by the structure is allocated from the memory provided with the buffer
       parameter, which is bufsize bytes in size. The maximum size needed for this buffer can be determined  with  the
       {_SC_GETPW_R_SIZE_MAX}  sysconf()  parameter.  A  NULL  pointer shall be returned at the location pointed to by
       result on error or if the requested entry is not found.

RETURN VALUE
       The getpwnam() function shall return a pointer to a struct passwd with the structure as defined in <pwd.h> with
       a  matching  entry  if found. A null pointer shall be returned if the requested entry is not found, or an error
       occurs. On error, errno shall be set to indicate the error.

       The return value may point to a static area which is overwritten by a subsequent  call  to  getpwent(),  getpw-
       nam(), or getpwuid().

       If  successful,  the  getpwnam_r()  function shall return zero; otherwise, an error number shall be returned to
       indicate the error.

ERRORS
       The getpwnam() and getpwnam_r() functions may fail if:

       EIO    An I/O error has occurred.

       EINTR  A signal was caught during getpwnam().

       EMFILE {OPEN_MAX} file descriptors are currently open in the calling process.

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


       The getpwnam_r() function may fail if:

       ERANGE Insufficient storage was supplied via buffer and bufsize to contain the data to  be  referenced  by  the
              resulting passwd structure.


       The following sections are informative.

EXAMPLES
   Getting an Entry for the Login Name
       The  following example uses the getlogin() function to return the name of the user who logged in; this informa-
       tion is passed to the getpwnam() function to get the user database entry for that user.


              #include <sys/types.h>
              #include <pwd.h>
              #include <unistd.h>
              #include <stdio.h>
              #include <stdlib.h>
              ...
              char *lgn;
              struct passwd *pw;
              ...
              if ((lgn = getlogin()) == NULL || (pw = getpwnam(lgn)) == NULL) {
                  fprintf(stderr, "Get of user information failed.\n"); exit(1);
              }
              ...

APPLICATION USAGE
       Three names associated with the current process can be determined: getpwuid( geteuid()) returns the name  asso-
       ciated with the effective user ID of the process; getlogin() returns the name associated with the current login
       activity; and getpwuid( getuid()) returns the name associated with the real user ID of the process.

       The getpwnam_r() function is thread-safe and returns values in a user-supplied buffer instead of possibly using
       a static data area that may be overwritten by each call.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       getpwuid(), the Base Definitions volume of IEEE Std 1003.1-2001, <limits.h>, <pwd.h>, <sys/types.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Stan-
       dard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base  Specifica-
       tions  Issue  6,  Copyright (C) 2001-2003 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 Stan-
       dard,  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 .



IEEE/The Open Group                  2003                         GETPWNAM(3P)