exit(n) [osx man page]

exit(n) 						       Tcl Built-In Commands							   exit(n)

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NAME

       exit - End the application

SYNOPSIS

       exit ?returnCode?
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DESCRIPTION

       Terminate the process, returning returnCode to the system as the exit status.  If returnCode is not specified then it defaults to 0.

EXAMPLE

       Since non-zero exit codes are usually interpreted as error cases by the calling process, the exit 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:
	      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...
		  exit 2
	      }

SEE ALSO

       exec(n)

KEYWORDS

       exit, process

Tcl																	   exit(n)

catch(n)						       Tcl Built-In Commands							  catch(n)

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NAME

       catch - Evaluate script and trap exceptional returns

SYNOPSIS

       catch script ?varName?
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DESCRIPTION

       The  catch command may be used to prevent errors from aborting command interpretation.  Catch calls the Tcl interpreter recursively to exe-
       cute script, and always returns without raising an error, regardless of any errors that might occur while executing script.

       If script raises an error, catch will return a non-zero integer value corresponding to one of the exceptional return codes (see	tcl.h  for
       the  definitions of code values).  If the varName argument is given, then the variable it names is set to the error message from interpret-
       ing script.

       If script does not raise an error, catch will return 0 (TCL_OK) and set the variable to the value returned from script.

       Note that catch catches all exceptions, including those generated by break and continue as well as errors.  The only errors  that  are  not
       caught  are  syntax  errors found when the script is compiled.  This is because the catch command only catches errors during runtime.  When
       the catch statement is compiled, the script is compiled as well and any syntax errors will generate a Tcl error.

EXAMPLES

       The catch command may be used in an if to branch based on the success of a script.

	      if { [catch {open $someFile w} fid] } {
		  puts stderr "Could not open $someFile for writing
$fid"
		  exit 1
	      }
       The catch command will not catch compiled syntax errors.  The first time proc foo is called, the body will be compiled and a Tcl error will
       be generated.

	      proc foo {} {
		  catch {expr {1 +- }}
	      }

SEE ALSO

       error(n), break(n), continue(n)

KEYWORDS

       catch, error

Tcl									8.0								  catch(n)