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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);


       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(), 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


       SVID 3, 4.3BSD, POSIX 1003.1-2003


       The  formulation  given  above  under  "RETURN  VALUE"  is  from  POSIX
       1003.1-2001.  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)