Provided by: manpages-dev_3.15-1_all bug

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 (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.

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: %ld0, pwd.pw_gecos, (long) pwd.pw_uid);
           exit(EXIT_SUCCESS);
       }

SEE ALSO

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

COLOPHON

       This  page  is  part of release 3.15 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/.