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


       #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 *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 ||


       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
       information, 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 <pwd.h> as follows:

           struct passwd {
               char   *pw_name;       /* user name */
               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
       _SC_GETPW_R_SIZE_MAX parameter.


       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

       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.


       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.


       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


       SVr4, 4.3BSD, POSIX.1-2001


       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.


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


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