source: downloads/tcl8.5.2/doc/exit.n @ 35

'\"
'\" 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.
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'\" RCS: @(#) $Id: exit.n,v 1.9 2007/12/13 15:22:32 dgp Exp $
'\" 
.so man.macros
.TH exit n "" Tcl "Tcl Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
exit \- End the application
.SH SYNOPSIS
\fBexit \fR?\fIreturnCode\fR?
.BE

.SH DESCRIPTION
.PP
Terminate the process, returning \fIreturnCode\fR to the
system as the exit status.
If \fIreturnCode\fR is not specified then it defaults
to 0.
.SH EXAMPLE
Since non-zero exit codes are usually interpreted as error cases by
the calling process, the \fBexit\fR command is an important part of
signaling that something fatal has gone wrong. This code fragment is
useful in scripts to act as a general problem trap:
.CS
proc main {} {
    # ... put the real main code in here ...
}

if {[catch {main} msg options]} {
    puts stderr "unexpected script error: $msg"
    if {[info exist env(DEBUG)]} {
        puts stderr "---- BEGIN TRACE ----"
        puts stderr [dict get $options -errorinfo]
        puts stderr "---- END TRACE ----"
    }

    # Reserve code 1 for "expected" error exits...
    \fBexit\fR 2
}
.CE

.SH "SEE ALSO"
exec(n)

.SH KEYWORDS
exit, process