20.3. cgitb — Traceback manager for CGI scripts¶
The cgitb module provides a special exception handler for Python scripts.
(Its name is a bit misleading. It was originally designed to display extensive
traceback information in HTML for CGI scripts. It was later generalized to also
display this information in plain text.) After this module is activated, if an
uncaught exception occurs, a detailed, formatted report will be displayed. The
report includes a traceback showing excerpts of the source code for each level,
as well as the values of the arguments and local variables to currently running
functions, to help you debug the problem. Optionally, you can save this
information to a file instead of sending it to the browser.
To enable this feature, simply add this to the top of your CGI script:
import cgitb
cgitb.enable()
The options to the enable() function control whether the report is
displayed in the browser and whether the report is logged to a file for later
analysis.
-
cgitb.enable([display[, logdir[, context[, format]]]])¶
This function causes the cgitb module to take over the interpreter’s
default handling for exceptions by setting the value of sys.excepthook.
The optional argument display defaults to 1 and can be set to 0 to
suppress sending the traceback to the browser. If the argument logdir is
present, the traceback reports are written to files. The value of logdir
should be a directory where these files will be placed. The optional argument
context is the number of lines of context to display around the current line
of source code in the traceback; this defaults to 5. If the optional
argument format is "html", the output is formatted as HTML. Any other
value forces plain text output. The default value is "html".
-
cgitb.handler([info])¶
This function handles an exception using the default settings (that is, show a
report in the browser, but don’t log to a file). This can be used when you’ve
caught an exception and want to report it using cgitb. The optional
info argument should be a 3-tuple containing an exception type, exception
value, and traceback object, exactly like the tuple returned by
sys.exc_info(). If the info argument is not supplied, the current
exception is obtained from sys.exc_info().