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       chown, fchown, lchown - change ownership of a file


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

       int chown(const char *path, uid_t owner, gid_t group);
       int fchown(int fd, uid_t owner, gid_t group);
       int lchown(const char *path, uid_t owner, gid_t group);


       These  system calls change the owner and group of the file specified by
       path or by  fd.   Only  a  privileged  process  (Linux:  one  with  the
       CAP_CHOWN  capability)  may change the owner of a file.  The owner of a
       file may change the group of the file to any group of which that  owner
       is  a  member.  A privileged process (Linux: with CAP_CHOWN) may change
       the group arbitrarily.

       If the owner or group is specified as -1, then that ID is not  changed.

       When  the  owner  or  group of an executable file are changed by a non-
       superuser, the S_ISUID and S_ISGID mode bits are  cleared.  POSIX  does
       not specify whether this also should happen when root does the chown();
       the Linux behaviour depends on the kernel version.  In case of  a  non-
       group-executable   file  (with  clear  S_IXGRP  bit)  the  S_ISGID  bit
       indicates mandatory locking, and is not cleared by a chown().


       On success, zero is returned.  On error, -1 is returned, and  errno  is
       set appropriately.


       Depending  on  the file system, other errors can be returned.  The more
       general errors for chown() are listed below.

       EACCES Search permission is denied on a component of the  path  prefix.
              (See also path_resolution(2).)

       EFAULT path points outside your accessible address space.

       ELOOP  Too many symbolic links were encountered in resolving path.

              path is too long.

       ENOENT The file does not exist.

       ENOMEM Insufficient kernel memory was available.

              A component of the path prefix is not a directory.

       EPERM  The  calling  process did not have the required permissions (see
              above) to change owner and/or group.

       EROFS  The named file resides on a read-only file system.

       The general errors for fchown() are listed below:

       EBADF  The descriptor is not valid.

       EIO    A low-level I/O error occurred while modifying the inode.

       ENOENT See above.

       EPERM  See above.

       EROFS  See above.


       In versions of Linux  prior  to  2.1.81  (and  distinct  from  2.1.46),
       chown()  did  not  follow  symbolic links.  Since Linux 2.1.81, chown()
       does follow symbolic links, and there is a  new  system  call  lchown()
       that does not follow symbolic links.  Since Linux 2.1.86, this new call
       (that has the same semantics as the  old  chown())  has  got  the  same
       syscall number, and chown() got the newly introduced number.

       The  prototype for fchown() is only available if _BSD_SOURCE is defined
       (either explicitly, or implicitly, by  not  defining  _POSIX_SOURCE  or
       compiling with the -ansi flag).


       The  chown()  call  conforms  to SVr4, SVID, POSIX, X/OPEN.  The 4.4BSD
       version can only be used by the  superuser  (that  is,  ordinary  users
       cannot  give  away  files).   SVr4 documents EINVAL, EINTR, ENOLINK and
       EMULTIHOP returns, but no ENOMEM.  POSIX.1 does not document ENOMEM  or
       ELOOP error conditions.

       The  fchown()  call  conforms  to  4.4BSD  and  SVr4.   SVr4  documents
       additional EINVAL, EIO, EINTR, and ENOLINK error conditions.


       The chown() semantics are deliberately violated  on  NFS  file  systems
       which  have  UID  mapping  enabled.  Additionally, the semantics of all
       system calls which access  the  file  contents  are  violated,  because
       chown()  may  cause  immediate access revocation on already open files.
       Client side caching  may  lead  to  a  delay  between  the  time  where
       ownership  have  been  changed  to allow access for a user and the time
       where the file can actually be accessed by the user on other clients.


       chmod(2), flock(2), path_resolution(2)