'\"
'\" Copyright (c) 1993 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" RCS: @(#) $Id: exec.n,v 1.10 2004/07/02 23:31:29 hobbs Exp $
'\" 
.so man.macros
.TH exec n 8.5 Tcl "Tcl Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
exec \- Invoke subprocess(es)
.SH SYNOPSIS
\fBexec \fR?\fIswitches\fR? \fIarg \fR?\fIarg ...\fR?
.BE

2>@\0\fIfileId\fR
\fIFileId\fR must be the identifier for an open file, such as the return
value from a previous call to \fBopen\fR.
Standard error from all commands in the pipeline is
redirected to \fIfileId\fR's file.
The file must have been opened for writing.
.TP 15
2>@1\0
Standard error from all commands in the pipeline is redirected to the
command result.  This operator is only valid at the end of the command
pipeline.
.TP 15
>&@\0\fIfileId\fR
\fIFileId\fR must be the identifier for an open file, such as the return
value from a previous call to \fBopen\fR.
Both standard output from the last command and standard error from
all commands are redirected to \fIfileId\fR's file.
The file must have been opened for writing.
.PP
If standard output has not been redirected then the \fBexec\fR
command returns the standard output from the last command
in the pipeline,
.VS 8.5
unless ``2>@1'' was specified, in which case
standard error is included as well.
.VE 8.5
If any of the commands in the pipeline exit abnormally or
are killed or suspended, then \fBexec\fR will return an error
and the error message will include the pipeline's output followed by
error messages describing the abnormal terminations; the
\fBerrorCode\fR variable will contain additional information
about the last abnormal termination encountered.
If any of the commands writes to its standard error file and that

.RE
.sp
In order to execute the shell builtin commands like \fBdir\fR and \fBcopy\fR,
the caller must prepend ``\fBcmd.exe /c\0\fR'' to the desired command.
.sp
.RE
.TP
\fBWindows 9x\fR
.
When attempting to execute an application, \fBexec\fR first searches for
the name as it was specified.  Then, in order, \fB.com\fR, \fB.exe\fR, and
\fB.bat\fR are appended to the end of the specified name and it searches
for the longer name.  If a directory name was not specified as part of the
application name, the following directories are automatically searched in
order when attempting to locate the application:
.sp
.RS
.RS
The directory from which the Tcl executable was loaded.
.br
The current directory.
.br
The Windows 9x system directory.
.br
The Windows 9x home directory.
.br
The directories listed in the path.
.RE
.sp
In order to execute the shell builtin commands like \fBdir\fR and \fBcopy\fR,
the caller must prepend ``\fBcommand.com /c\0\fR'' to the desired command.
.sp