Logging elsewhere

Vortex error messages can be logged to another file besides the default /usr/local/morph3/texis/vortex.log . For command-line scripts, the option -e specifies where to log them. For Web scripts, and to change the overall default log file, the /usr/local/morph3/texis.cnf file can be edited.

Stopping messages, capturing in-script

A script can monitor its own error messages to detect and possibly correct errors on the fly. If a putmsg script function is present in a script, it will be called whenever errors are generated. Several variables are set by Vortex when the function is called. These variables are in a parallel loop, one value per message, since several message may be queued up by the time it's safe to call putmsg :

• errnum
  The error number

• errscript
  The script file or module where the error occurred

• errline
  The line in the script or module where the error occurred

• errmsg
  The text of the message

• errfunc
  The internal C function it occurred in The Vortex function it occurred in

When putmsg is defined, errors will go to that function, and will not be logged or printed to the output. It is up to the putmsg to dispose of the messages: log them, print them, warn the user, etc. A sample putmsg function that scans for specific errors might look like this:

  <A NAME=putmsg PRIVATE>
    <LOOP $errnum $errscript $errline $errmsg $errfunc>
      <strstr "<EXEC> command" $errmsg>
      <IF $ret neq "">
        <B>The EXEC failed</B>
        <$BadExec = y>
      </IF>
      <B>$errnum $errscript:$errline $errmsg in $errfunc
    </LOOP>
  </A>

  <A NAME=otherfunc>
    <$BadExec = n>
    <EXEC /no/such/program></EXEC>
    <IF $BadExec eq "y">
      <EXEC /some/other/program></EXEC>
    </IF>
  </A>

Here we scan the errors in putmsg for messages about <EXEC> failing. <EXEC> runs external programs, so it commonly generates errors, eg. if the program is not found or exits with an error. We set the flag $BadExec to y if it fails. Regardless of the error message, we print it out in bold so we can see it.

In otherfunc , we try to run /no/such/program . This fails, generating an error. putmsg is thus called, sees the <EXEC> error, and sets our flag. We can then check this flag back in otherfunc : if our <EXEC> failed, we try it again with a new path.