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GETPWNAM(3)                Linux Programmer's Manual               GETPWNAM(3)



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

SYNOPSIS
       #include <&lt;sys/types.h>&gt;
       #include <&lt;pwd.h>&gt;

       struct passwd *getpwnam(const char *name);

       struct passwd *getpwuid(uid_t uid);

       int getpwnam_r(const char *name, struct passwd *pwbuf,
                   char *buf, size_t buflen, struct passwd **pwbufp);

       int getpwuid_r(uid_t uid, struct passwd *pwbuf,
                   char *buf, size_t buflen, struct passwd **pwbufp);

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

       getpwnam_r(), getpwuid_r(): _POSIX_C_SOURCE || _XOPEN_SOURCE ||
       _BSD_SOURCE || _SVID_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  user-
       name 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 informa-
       tion, but store the retrieved passwd structure in the space pointed  to
       by  pwbuf.   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 *pwbufp.

       The passwd structure is defined in &lt;pwd.h&gt; 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().

       The getpwnam_r() and getpwuid_r() functions return zero on success.  In
       case of error, an error number is returned.

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 var-
       ious 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())-&gt;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")-&gt;pw_dir or similar.

SEE ALSO
       endpwent(3), fgetpwent(3), getgrnam(3),  getpw(3),  getpwent(3),  putp-
       went(3), setpwent(3), nsswitch.conf(5), passwd(5)

COLOPHON
       This  page  is  part of release 3.05 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/.



GNU                               2007-07-26                       GETPWNAM(3)