#!/bin/sh
LOG_FILE="log.txt"
TMP_DIR="/tmp"
TIMEOUT=10
echo "Content-type: text/html"
echo
echo
echo "Hello"
myname=`basename $0`
LOCK_NAME="lock.${myname}"
SELECTION=`echo ${QUERY_STRING} | sed 's/%3A/:/g' | cut -d= -f2`
SELECTION_FILE="data/${SELECTION}.txt"
USER=`echo "${REMOTE_USER}" | cut -d@ -f1`
# Make sure we've got a selection, or redirect back
if [ "${SELECTION}" == "" ] ; then
goto RedirectBack
exit
fi
if [ ! `ls ${SELECTION_FILE}` ] ; then
goto RedirectBack;
exit
fi
# Clear out stale lock files
stalefile=`find ${TMP_DIR} -name ${LOCK_NAME} -cmin +10 -print`
if [ "${stalefile}" != "" ]; then
stalepid=`cat ${TMP_DIR}/${LOCK_NAME}`
if kill -9 ${stalepid}
then
rm -f ${TMP_DIR}/${LOCK_NAME}
fi
fi
# Obtain mutex
trap "if [ grep -w $$ ${TMP_DIR}/${LOCK_NAME} ]; then \
rm -f ${TMP_DIR}/${LOCK_NAME} \
fi" 0
until (umask 222; echo $$ >${TMP_DIR}/$LOCK_NAME) 2>/dev/null # test & set
do
# Wait so we don't burn to much CPU
sleep 2
# Clear out the lock file, if it became stale
stalefile=`find ${TMP_DIR} -name ${LOCK_NAME} -cmin +${TIMEOUT} -print`
if [ "${stalefile}" != "" ]; then
rm -f ${TMP_DIR}/${LOCK_NAME}
fi
done
# Unregister user
for file in `ls data/*.txt`
do
file=`echo ${file} | cut -d/ -f2`
grep -wvh ${USER} data/${file} > /tmp/${file}.$$
rm -f data/${file}
mv /tmp/${file}.$$ data/${file}
done
echo "${USER} ${SELECTION}" >> ${LOG_FILE}
RedirectBack:
echo ${USER} >> ${SELECTION_FILE}
echo ""
echo " "
echo " "
echo " 15-123 Spring 2007 Final Exam Signups"
echo " "
echo " "
echo " Redirecting you to Operation complete, redirecting you to see results"
echo " "
echo " "
# rm -f ${TMP_DIR}/${LOCK_NAME}