Converting a date to unix epoch

Here is a very simple C program that will allow you to convert a date to the Unix epoch (number of seconds since 1st of January 1970). Click here to download it.To compile it, use the following syntax :
gcc date2epoch.c -o date2epoch
If we run it without argument, we see the usage below :
Usage: ./date2epoch date
Where date is specified according to date mask file.
eg. : if you want to specify a date as 11/11/03 12:39, you need
to create a file datemsk with the string "%D %H:%M", then export
the date file mask with the command : export DATEMSK=/path/datemsk
Then, call this program with the following command :
./date2epoch "`date "+%D %H:%M"`" or ./date2epoch "11/11/03 12:39"

So, in order to use it, we need to create a datemsk file with the following command :
echo "%D %H:%M" > /usr/local/bin/datemsk
You can choose any format as long as you remember it when you will run date2epoch.