Dynamic (CGI) Web page hosting at www.nmt.edu

CGI scripting allows you to set up pages whose content is generated dynamically each time a URL is accessed. See `Web features: the major parts of HTML' for references on how to do CGI scripting.

For security reasons, CGI scripts must obey certain rules. If you fail to conform to these rules, your page may not be available to readers, who will get an error 403 or other access error.

These instructions assume you are familiar with Unix-related concepts such as ownership and permissions. See `Unix fundamentals' for a basic Unix tutorial.

• When a CGI script executes, it has the same identity and permissions as the owner of that script. If, for example, you own a script and it needs to write to a file, it can write to any file for which you have write permission. (Before August 2003, all scripts ran as user nobody, a placeholder user with no special permissions.)
• A CGI script may not be a soft link. It must be an actual file.
• The script must be in or under your ~/public_html directory.
• The script cannot be world or group writeable.
• Make sure that the group ownership of your ~/public_html directory, and all other directories and files involved, is a group that includes you. Type the "groups" command to get a list of your group membership. Use the "ls -l" command to show the group ownerships of your files. For example, in this line of output from "ls -l", the group ownership of the file is 8976.

  -rw-r--r--    1 8976           18 Dec  4  2004 abc
  

• Formerly, any error output (to stdout) from a script was appended to the Apache error log. However, that log is now inaccessible. Since your script runs as you, you can write debug output to any file to which you have write access, and that file does not need to be world-writeable or even world-readable.
• If you use server side includes, any script invoked by <!--exec cmd="..."--> must be in the same directory and cannot have any command line arguments.
• Your user ID number must be greater than 500. Some older accounts may have this problem. Ask the User Consultant if you are not sure about your user ID number.
• Previously, CGI scripts had to end in .cgi. Now, they may also end in .pl (Perl) or .py (Python).

Last updated: 2005/07/21 21:43:59 UT
URL: http://www.nmt.edu/tcc/help/html/host_cgi.html