The following is the output of /usr/bin/cal. Can only run commands in /usr/bin and your CGI directories.
GEOIP_COUNTRY_CODE=US
GEOIP_COUNTRY_NAME=United States
SCRIPT_URL=/dev/doc/Try_Me/test_exec.html
SCRIPT_URI=http://www.math.utexas.edu/dev/doc/Try_Me/test_exec.html
HTTP_X_CC_ID=ccc03-02
HTTP_HOST=www.math.utexas.edu
HTTP_USER_AGENT=CCBot/1.0 (+http://www.commoncrawl.org/bot.html)
HTTP_ACCEPT=text/html,application/xhtml+xml,text/xml;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
HTTP_ACCEPT_LANGUAGE=en-us,en;q=0.5
HTTP_ACCEPT_ENCODING=gzip
HTTP_ACCEPT_CHARSET=ISO-8859-1,utf-8;q=0.7,*;q=0.7
HTTP_CONNECTION=close
HTTP_CACHE_CONTROL=no-cache
HTTP_PRAGMA=no-cache
HTTP_COOKIE=PHPSESSID=2bc9890dbae706cf8bf69a86769f496b
PATH=/bin:/usr/bin
SERVER_SIGNATURE=Apache/2.2.12 (Ubuntu) Server at www.math.utexas.edu Port 80
SERVER_SOFTWARE=Apache/2.2.12 (Ubuntu)
SERVER_NAME=www.math.utexas.edu
SERVER_ADDR=146.6.139.68
SERVER_PORT=80
REMOTE_ADDR=38.107.179.232
DOCUMENT_ROOT=/d/www
SERVER_ADMIN=webmaster@math.utexas.edu
SCRIPT_FILENAME=/d/www/cgi-bin/cms/pub/body
REMOTE_PORT=57506
GATEWAY_INTERFACE=CGI/1.1
SERVER_PROTOCOL=INCLUDED
REQUEST_METHOD=GET
QUERY_STRING=
REQUEST_URI=/dev/doc/Try_Me/test_exec.html
SCRIPT_NAME=/cgi-bin/cms/pub/body
DATE_LOCAL=
DATE_GMT=
LAST_MODIFIED=
DOCUMENT_URI=/dev/doc/Try_Me/test_exec.html
USER_NAME=
DOCUMENT_NAME=test_exec.html