• NAME
  
  getpwnam, getpwnam_r, getpwuid, getpwuid_r - get password file entry
• SYNOPSIS
  

  
   #include <sys/types.h>
   #include <pwd.h>
  
   struct passwd *getpwnam(const char * name );
  
  
      struct passwd *getpwuid(uid_t  uid ); 
  
      int getpwnam_r(const char * name , struct passwd * pwd , 
   
  
                char * buf , size_t  buflen , struct passwd ** result ); 
  
      int getpwuid_r(uid_t  uid , struct passwd * pwd , 
   
  
                char * buf , size_t  buflen , struct passwd ** result ); 
  
    Feature Test Macro Requirements for glibc (see
  
  
    feature_test_macros(7) ):
  
   
  
      getpwnam_r (),
  
     getpwuid_r ():
  
   _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _BSD_SOURCE ||
  
  
  _SVID_SOURCE || _POSIX_SOURCE
  
  
  

• DESCRIPTION
  
  The
  getpwnam ()
  function returns a pointer to a structure containing
  the broken-out fields of the record in the password database
  (e.g., the local password file
  /etc/passwd ,
  NIS, and LDAP)
  that matches the username
  name .
  
  
  
  The
  getpwuid ()
  function returns a pointer to a structure containing
  the broken-out fields of the record in the password database
  that matches the user ID
  uid .
  
  
  
  The
  getpwnam_r ()
  and
  getpwuid_r ()
  functions obtain the same information, but store the retrieved
  passwd
  structure in the space pointed to by
  pwd .
  This
  passwd
  structure contains pointers to strings, and these strings
  are stored in the buffer
  buf
  of size
  buflen .
  A pointer to the result (in case of success) or NULL (in case no entry
  was found or an error occurred) is stored in
  *result .
  
  
  
  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;      /* real name */
      char   *pw_dir;        /* home directory */
      char   *pw_shell;      /* shell program */
  };
  

  
  
  The maximum needed size for buf can be found using sysconf(3) with the argument _SC_GETPW_R_SIZE_MAX .
• RETURN VALUE
  
  The getpwnam () and getpwuid () functions return a pointer to a passwd structure, or NULL if the matching entry is not found or an error occurs. 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 static area, and may be overwritten by subsequent calls to getpwent(3) , getpwnam (), or getpwuid (). On success, getpwnam_r () and getpwuid_r () return zero, and set *result to pwd . If no matching password record was found, these functions return 0 and store NULL in *result . In case of error, an error number is returned, and NULL is stored in *result .
• ERRORS
  

  0 " or " ENOENT " or " ESRCH " or " EBADF " or " EPERM " or ... "

  The given name or uid was not found.

  EINTR

  A signal was caught.

  EIO

  I/O error.

  EMFILE

  The maximum number of files was open already in the calling process.

  ENFILE

  The maximum number of files was open already in the system.

  ENOMEM

  Insufficient memory to allocate passwd structure.

  ERANGE

  Insufficient buffer space supplied.

• FILES
  

  /etc/passwd

  local password database file

• CONFORMING TO
  
  SVr4, 4.3BSD, POSIX.1-2001.
• NOTES
  
  The formulation given above under "RETURN VALUE" is from POSIX.1-2001. It does not call "not found" an error, and hence does not specify what value errno might have in this situation. But that makes it impossible to recognize errors. One might argue that according to POSIX errno should be left unchanged if an entry is not found. Experiments on various Unix-like systems show that lots of different values occur in this situation: 0, ENOENT, EBADF, ESRCH, EWOULDBLOCK, EPERM and probably others.
  The pw_dir field contains the name of the initial working directory of the user. Login programs use the value of this field to initialize the HOME environment variable for the login shell. An application that wants to determine its user's home directory should inspect the value of HOME (rather than the value getpwuid(getuid())->pw_dir ) since this allows the user to modify their notion of "the home directory" during a login session. To determine the (initial) home directory of another user, it is necessary to use getpwnam("username")->pw_dir or similar.
• EXAMPLE
  
  The program below demonstrates the use of getpwnam_r () to find the full username and user ID for the username supplied as a command-line argument.
  

  
  #include <pwd.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <unistd.h>
  #include <errno.h>
  
  int
  main(int argc, char *argv[])
  {
      struct passwd pwd;
      struct passwd *result;
      char *buf;
      size_t bufsize;
      int s;
  
      if (argc != 2) {
          fprintf(stderr, "Usage: %s username\n", argv[0]);
          exit(EXIT_FAILURE);
      }
  
      bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
      if (bufsize == -1)          /* Value was indeterminate */
          bufsize = 16384;        /* Should be more than enough */
  
      buf = malloc(bufsize);
      if (buf == NULL) {
          perror("malloc");
          exit(EXIT_FAILURE);
      }
  
      s = getpwnam_r(argv[1], &pwd, buf, bufsize, &result);
      if (result == NULL) {
          if (s == 0)
              printf("Not found\n");
          else {
              errno = s;
              perror("getpwnam_r");
          }
          exit(EXIT_FAILURE);
      }
  
      printf("Name: %s; UID: %ldn", pwd.pw_gecos, (long) pwd.pw_uid);
      exit(EXIT_SUCCESS);
  }
  

• SEE ALSO
  
  endpwent(3) , fgetpwent(3) , getgrnam(3) , getpw(3) , getpwent(3) , getspnam(3) , putpwent(3) , setpwent(3) , passwd(5)
• COLOPHON
  
  This page is part of release 3.19 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.

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