fchown(2)

1CHOWN(2)                   Linux Programmer's Manual                  CHOWN(2)
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NAME

6       chown, fchown, lchown - change ownership of a file
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SYNOPSIS

9       #include <sys/types.h>
10       #include <unistd.h>
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12       int chown(const char *path, uid_t owner, gid_t group);
13       int fchown(int fd, uid_t owner, gid_t group);
14       int lchown(const char *path, uid_t owner, gid_t group);
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DESCRIPTION

17       These  system calls change the owner and group of the file specified by
18       path or by  fd.   Only  a  privileged  process  (Linux:  one  with  the
19       CAP_CHOWN  capability)  may change the owner of a file.  The owner of a
20       file may change the group of the file to any group of which that  owner
21       is  a  member.  A privileged process (Linux: with CAP_CHOWN) may change
22       the group arbitrarily.
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24       If the owner or group is specified as -1, then that ID is not changed.
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26       When the owner or group of an executable file are  changed  by  a  non-
27       superuser,  the  S_ISUID  and S_ISGID mode bits are cleared. POSIX does
28       not specify whether this also should happen when root does the chown();
29       the  Linux  behaviour depends on the kernel version.  In case of a non-
30       group-executable file (with clear S_IXGRP bit) the  S_ISGID  bit  indi‐
31       cates mandatory locking, and is not cleared by a chown().
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RETURN VALUE

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

38       Depending on the file system, other errors can be returned.   The  more
39       general errors for chown() are listed below.
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41       EACCES Search  permission  is denied on a component of the path prefix.
42              (See also path_resolution(2).)
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44       EFAULT path points outside your accessible address space.
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46       ELOOP  Too many symbolic links were encountered in resolving path.
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48       ENAMETOOLONG
49              path is too long.
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51       ENOENT The file does not exist.
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53       ENOMEM Insufficient kernel memory was available.
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55       ENOTDIR
56              A component of the path prefix is not a directory.
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58       EPERM  The calling process did not have the required  permissions  (see
59              above) to change owner and/or group.
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61       EROFS  The named file resides on a read-only file system.
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63       The general errors for fchown() are listed below:
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65       EBADF  The descriptor is not valid.
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67       EIO    A low-level I/O error occurred while modifying the inode.
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69       ENOENT See above.
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71       EPERM  See above.
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73       EROFS  See above.
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NOTES

76       In  versions  of  Linux  prior  to  2.1.81  (and distinct from 2.1.46),
77       chown() did not follow symbolic links.   Since  Linux  2.1.81,  chown()
78       does  follow  symbolic  links,  and there is a new system call lchown()
79       that does not follow symbolic links.  Since Linux 2.1.86, this new call
80       (that  has  the  same  semantics  as  the old chown()) has got the same
81       syscall number, and chown() got the newly introduced number.
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83       The prototype for fchown() is only available if _BSD_SOURCE is defined.
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CONFORMING TO

86       4.4BSD, SVr4, POSIX.1-2001.
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88       The 4.4BSD version can only be used by the superuser (that is, ordinary
89       users cannot give away files).
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RESTRICTIONS

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