The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.
A newer edition of this document exists here


fdetach - detach a name from a STREAMS-based file descriptor (STREAMS)


[XSR] [Option Start] #include <stropts.h>

int fdetach(const char *
path); [Option End]


The fdetach() function shall detach a STREAMS-based file from the file to which it was attached by a previous call to fattach(). The path argument points to the pathname of the attached STREAMS file. The process shall have appropriate privileges or be the owner of the file. A successful call to fdetach() shall cause all pathnames that named the attached STREAMS file to again name the file to which the STREAMS file was attached. All subsequent operations on path shall operate on the underlying file and not on the STREAMS file.

All open file descriptions established while the STREAMS file was attached to the file referenced by path shall still refer to the STREAMS file after the fdetach() has taken effect.

If there are no open file descriptors or other references to the STREAMS file, then a successful call to fdetach() shall be equivalent to performing the last close() on the attached file.


Upon successful completion, fdetach() shall return 0; otherwise, it shall return -1 and set errno to indicate the error.


The fdetach() function shall fail if:

Search permission is denied on a component of the path prefix.
The path argument names a file that is not currently attached.
A loop exists in symbolic links encountered during resolution of the path argument.
The size of a pathname exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.
A component of path does not name an existing file or path is an empty string.
A component of the path prefix is not a directory.
The effective user ID is not the owner of path and the process does not have appropriate privileges.

The fdetach() function may fail if:

More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the path argument.
Pathname resolution of a symbolic link produced an intermediate result whose length exceeds {PATH_MAX}.

The following sections are informative.


Detaching a File

The following example detaches the STREAMS-based file /tmp/named-STREAM from the file to which it was attached by a previous, successful call to fattach(). Subsequent calls to open this file refer to the underlying file, not to the STREAMS file.

#include <stropts.h>
    char *filename = "/tmp/named-STREAM";
    int ret;

ret = fdetach(filename);








fattach(), the Base Definitions volume of IEEE Std 1003.1-2001, <stropts.h>


First released in Issue 4, Version 2.

Issue 5

Moved from X/OPEN UNIX extension to BASE.

Issue 6

The DESCRIPTION is updated to avoid use of the term "must" for application requirements.

The wording of the mandatory [ELOOP] error condition is updated, and a second optional [ELOOP] error condition is added.

End of informative text.

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