Shell Programming and Scripting

#!/bin/bash
MAXTRIES=10
TRIES=0
COUNT=0

# mkfifo will fail whenever something else is already using the count file
while ! mkfifo /tmp/count-fifo 2>/dev/null
do
        sleep 0.1
        ((TRIES++))
        # 'internal server error' if we can't create the fifo
        [ "$TRIES" -ge "$MAXTRIES" ] && exit 1
done

# If we made it this far, we have the fifo.

# Read the last count, if there is one.
[ -f /tmp/count ] && read COUNT < /tmp/count

# Increment it.
((COUNT++))

# Write COUNT to the file
echo "$COUNT" > /tmp/count

# Delete the fifo, letting other things use the file.
rm /tmp/count-fifo

echo 'content-type: text/html'
echo
echo 'script Counter<br>'
echo "Count is $COUNT"



exit 0