18.2.10 Common problems and solutions

Most HTTP servers buffer the output from CGI scripts until the script is completed. This means that it is not possible to display a progress report on the client's display while the script is running.
Check the installation instructions above.
Check the HTTP server's log files. ("tail -f logfile" in a separate window may be useful!)
Always check a script for syntax errors first, by doing something like "python script.py".
If your script does not have any syntax errors, try adding "import cgitb; cgitb.enable()" to the top of the script.
When invoking external programs, make sure they can be found. Usually, this means using absolute path names -- PATH is usually not set to a very useful value in a CGI script.
When reading or writing external files, make sure they can be read or written by the userid under which your CGI script will be running: this is typically the userid under which the web server is running, or some explicitly specified userid for a web server's "suexec" feature.
Don't try to give a CGI script a set-uid mode. This doesn't work on most systems, and is a security liability as well.

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