Passing parameters to a CGI script

Some important points:

The CGI script has to end with .cgi in the name

It can be placed anywhere in your folder ~/html

It has to have secure web permissions set – run mkhomepg

CGI parameters are passed after ? in the URL, for example: https://hangar118.sdf.org/cgi-bin/foo.cgi?a=1;b=2

The CGI script gets the parameters via the environment variable QUERY_STRING

Example session:

# Folder for CGI scripts
$ mkdir ~/html/cgi-bin

# Create file such a this
$ cat ~/html/cgi-bin/foo.cgi
#!/usr/bin/bash
echo 'Content-type: text/html'
echo ''
echo '<html>'
echo '<head>'
echo '<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">'
echo '</head>'
echo '<body>'

echo '<p>Hello World!</p>'

echo '<pre>'

echo "Query (after '?' in the URL): ${QUERY_STRING}"
echo "From: ${HTTP_USER_AGENT}"

echo '</pre>'

echo '</body>'
echo '</html>'
exit 0

# Set executable attribute
$ chmod +x foo.cgi

# Set secure web permissions
$ mkhomepg
setting secure web permissions for /meta/www/h/hangar118
% queing permissions to be set

# Correct permissions would look like this
$ ls -l ~/html/cgi-bin/
total 4.0K
-rwxr-x--- 1 hangar118 www-data 368 Jan  3 02:21 foo.cgi*

It can be invoked via https://hangar118.sdf.org/cgi-bin/foo.cgi?a=1;b=2

Then, in the browser it will produce an output similar to this:

Hello World!

Query (after '?' in the URL): a=1;b=2
From: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/109.0

NOTE: The example session is from the MetaArray