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       getpwnam, getpwnam_r, getpwuid, getpwuid_r - get password file entry


       Standard C library (libc, -lc)


       #include <sys/types.h>
       #include <pwd.h>

       struct passwd *getpwnam(const char *name);
       struct passwd *getpwuid(uid_t uid);

       int getpwnam_r(const char *restrict name, struct passwd *restrict pwd,
                      char buf[restrict .buflen], size_t buflen,
                      struct passwd **restrict result);
       int getpwuid_r(uid_t uid, struct passwd *restrict pwd,
                      char buf[restrict .buflen], size_t buflen,
                      struct passwd **restrict result);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       getpwnam_r(), getpwuid_r():
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE


       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 call


       returns either -1, without changing errno, or an initial suggested size for buf.  (If this
       size  is  too small, the call fails with ERANGE, in which case the caller can retry with a
       larger buffer.)


       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 to
       indicate the error.  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.


       0 or ENOENT or ESRCH or EBADF or EPERM or ...
              The given name or uid was not found.

       EINTR  A signal was caught; see signal(7).

       EIO    I/O error.

       EMFILE The per-process limit on the number of open file descriptors has been reached.

       ENFILE The system-wide limit on the total number of open files has been reached.

       ENOMEM Insufficient memory to allocate passwd structure.

       ERANGE Insufficient buffer space supplied.


       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.


              local password database file

              System Databases and Name Service Switch configuration file


       For an explanation of the terms used in this section, see attributes(7).

       │InterfaceAttributeValue                                                    │
       │getpwnam()    │ Thread safety │ MT-Unsafe race:pwnam locale                              │
       │getpwuid()    │ Thread safety │ MT-Unsafe race:pwuid locale                              │
       │getpwnam_r(), │ Thread safety │ MT-Safe locale                                           │
       │getpwuid_r()  │               │                                                          │


       POSIX.1-2001,  POSIX.1-2008,  SVr4, 4.3BSD.  The pw_gecos field is not specified in POSIX,
       but is present on most implementations.


       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.


       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 <errno.h>
       #include <pwd.h>
       #include <stdint.h>
       #include <stdio.h>
       #include <stdlib.h>
       #include <unistd.h>

       main(int argc, char *argv[])
           struct passwd pwd;
           struct passwd *result;
           char *buf;
           long bufsize;
           int s;

           if (argc != 2) {
               fprintf(stderr, "Usage: %s username\n", argv[0]);

           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) {

           s = getpwnam_r(argv[1], &pwd, buf, bufsize, &result);
           if (result == NULL) {
               if (s == 0)
                   printf("Not found\n");
               else {
                   errno = s;

           printf("Name: %s; UID: %jd\n", pwd.pw_gecos,
                  (intmax_t) pwd.pw_uid);


       endpwent(3), fgetpwent(3), getgrnam(3), getpw(3), getpwent(3),  getspnam(3),  putpwent(3),
       setpwent(3), nsswitch.conf(5), passwd(5)