'\"
'\" Copyright (c) 1996-1997 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\" RCS: @(#) $Id: GetOpnFl.3,v 1.14 2007/12/13 15:22:31 dgp Exp $
.so man.macros
.TH Tcl_GetOpenFile 3 8.0 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_GetOpenFile \- Return a FILE* for a channel registered in the given interpreter (Unix only)
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
int
\fBTcl_GetOpenFile\fR(\fIinterp, chanID, write, checkUsage, filePtr\fR)
.sp
.SH ARGUMENTS
.AS Tcl_Interp checkUsage out
.AP Tcl_Interp *interp in
Tcl interpreter from which file handle is to be obtained.
.AP "const char" *chanID in
String identifying channel, such as \fBstdin\fR or \fBfile4\fR.
.AP int write in
Non-zero means the file will be used for writing, zero means it will
be used for reading.
.AP int checkUsage in
If non-zero, then an error will be generated if the file was not opened
for the access indicated by \fIwrite\fR.
.AP ClientData *filePtr out
Points to word in which to store pointer to FILE structure for
the file given by \fIchanID\fR.
.BE

.SH DESCRIPTION
.PP
\fBTcl_GetOpenFile\fR takes as argument a file identifier of the form
returned by the \fBopen\fR command and
returns at \fI*filePtr\fR a pointer to the FILE structure for
the file.
The \fIwrite\fR argument indicates whether the FILE pointer will
be used for reading or writing.
In some cases, such as a channel that connects to a pipeline of
subprocesses, different FILE pointers will be returned for reading
and writing.
\fBTcl_GetOpenFile\fR normally returns \fBTCL_OK\fR.
If an error occurs in \fBTcl_GetOpenFile\fR (e.g. \fIchanID\fR did not
make any sense or \fIcheckUsage\fR was set and the file was not opened
for the access specified by \fIwrite\fR) then \fBTCL_ERROR\fR is returned
and the interpreter's result will contain an error message.
In the current implementation \fIcheckUsage\fR is ignored and consistency
checks are always performed.
.PP
Note that this interface is only supported on the Unix platform.

.SH KEYWORDS
channel, file handle, permissions, pipeline, read, write