The Open Group Base Specifications Issue 7
IEEE Std 1003.1-2008, 2016 Edition
Copyright © 2001-2016 The IEEE and The Open Group

#### NAME

> fchown - change owner and group of a file

#### SYNOPSIS

> ``#include <unistd.h>
> int fchown(int` fildes`, uid_t` owner`, gid_t` group`);
> ``

#### DESCRIPTION

> The fchown() function shall be equivalent to chown() except that the file whose owner and group are changed is specified by the file descriptor fildes.

#### RETURN VALUE

> Upon successful completion, fchown() shall return 0. Otherwise, it shall return -1 and set errno to indicate the error.

#### ERRORS

> The fchown() function shall fail if:

> [EBADF]
>   The fildes argument is not an open file descriptor.
> [EPERM]
>   The effective user ID does not match the owner of the file or the process does not have appropriate privileges and _POSIX_CHOWN_RESTRICTED indicates that such privilege is required.
> [EROFS]
>   The file referred to by fildes resides on a read-only file system.

> The fchown() function may fail if:

> [EINVAL]
>   The owner or group ID is not a value supported by the implementation. The fildes argument refers to a pipe or socket [OB XSR] or an fattach()-ed STREAM and the implementation disallows execution of fchown() on a pipe.
> [EIO]
>   A physical I/O error has occurred.
> [EINTR]
>   The fchown() function was interrupted by a signal which was caught.

The following sections are informative.

#### EXAMPLES

> ##### Changing the Current Owner of a File

> The following example shows how to change the owner of a file named /home/cnd/mod1 to "jones" and the group to "cnd".

> The numeric value for the user ID is obtained by extracting the user ID from the user database entry associated with "jones". Similarly, the numeric value for the group ID is obtained by extracting the group ID from the group database entry associated with "cnd". This example assumes the calling program has appropriate privileges.

>     #include <sys/types.h>
>     #include <unistd.h>
>     #include <fcntl.h>
>     #include <pwd.h>
>     #include <grp.h>

>     struct passwd *pwd;
>     struct group  *grp;
>     int            fildes;
>     ...
>     fildes = open("/home/cnd/mod1", O_RDWR);
>     pwd = getpwnam("jones");
>     grp = getgrnam("cnd");
>     fchown(fildes, pwd->pw_uid, grp->gr_gid);

#### APPLICATION USAGE

> None.

#### RATIONALE

> None.

#### FUTURE DIRECTIONS

> None.

#### SEE ALSO

> chown

> XBD <unistd.h>

#### CHANGE HISTORY

> First released in Issue 4, Version 2.

#### Issue 5

> Moved from X/OPEN UNIX extension to BASE.

#### Issue 6

> The following changes were made to align with the IEEE P1003.1a draft standard:

> - Clarification is added that a call to fchown() may not be allowed on a pipe.

> The fchown() function is defined as mandatory.

#### Issue 7

> Functionality relating to XSI STREAMS is marked obsolescent.

End of informative text.

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