'\"
'\" Copyright (c) 1996 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" SCCS: @(#) GetOpnFl.3 1.2 96/03/26 13:40:26
.so man.macros
.TH Tcl_GetOpenFile 3 7.5 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_GetOpenFile \- Get a standard IO File * handle from a channel.
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
int
\fBTcl_GetOpenFile\fR(\fIinterp, string, write, checkUsage, filePtr\fR)
.sp
.SH ARGUMENTS
.AS Tcl_Interp checkUsage
.AP Tcl_Interp *interp in
Tcl interpreter from which file handle is to be obtained.
.AP char *string 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 wasn't 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 \fIstring\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 TCL_OK.
If an error occurs in \fBTcl_GetOpenFile\fR (e.g. \fIstring\fR didn't
make any sense or \fIcheckUsage\fR was set and the file wasn't opened
for the access specified by \fIwrite\fR) then TCL_ERROR is returned
and \fIinterp->result\fR will contain an error message.
In the current implementation \fIcheckUsage\fR is ignored and consistency
checks are always performed.

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