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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 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 */
           };

       See passwd(5) for more information about these fields.

       The getpwnam_r() and getpwuid_r() functions obtain the same information as getpwnam()  and
       getpwuid(),  but store the retrieved passwd structure in the space pointed to by pwd.  The
       string fields pointed to by the members of the passwd structure 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 maximum size  needed  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 a static area, and may be overwritten by subsequent calls to
       getpwent(3), getpwnam(), or getpwuid().  (Do not pass the returned pointer to free(3).)

       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 (OPEN_MAX) 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.

NOTE

       The  user password database mostly refers to /etc/passwd.  However, with recent systems it
       also refers to network wide databases using NIS, LDAP and other local files as  configured
       in /etc/nsswitch.conf.

FILES

       /etc/passwd
              local password database file

       /etc/nsswitch.conf
              System Databases and Name Service Switch configuration file

CONFORMING TO

       SVr4,  4.3BSD, POSIX.1-2001.  The pw_gecos field is not specified in POSIX, but is present
       on most implementations.

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: %ld\n", 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), nsswitch.conf(5), passwd(5)

COLOPHON

       This  page  is  part of release 3.35 of the Linux man-pages project.  A description of the
       project, and information about reporting bugs, can be found at  http://man7.org/linux/man-
       pages/.