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CHOWN(2)                   Linux Programmer's Manual                  CHOWN(2)



NAME
       chown, fchown, lchown - change ownership of a file

SYNOPSIS
       #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);

DESCRIPTION
       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().

RETURN VALUE
       On success, zero is returned.  On error, -1 is returned, and errno is set appropri-
       ately.

ERRORS
       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.

       ENAMETOOLONG
              path is too long.

       ENOENT The file does not exist.

       ENOMEM Insufficient kernel memory was available.

       ENOTDIR
              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.

NOTES
       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.

CONFORMING TO
       4.4BSD, SVr4, POSIX.1-2001.

       The  4.4BSD version can only be used by the superuser (that is, ordinary users can-
       not give away files).

RESTRICTIONS
       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.

SEE ALSO
       chmod(2), fchownat(2), flock(2), path_resolution(2)



Linux 2.6.7                       2004-06-23                          CHOWN(2)

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