Create a ISO file in linux

How to create a iso file?
Forget about Nero, forget about MagicISO. These windows software just waste time and money. In Linux everything is just a line of command.

>dd if=/dev/cdrom of=2440.iso
5597332+0 records in
5597332+0 records out
2865833984 bytes (2.9 GB) copied, 430.944 s, 6.7 MB/s

Maybe you want to mount this iso file
> mkdir /dev/2440
>mount -o loop 2440.iso /dev/2440/

Or you want to mount the iso file at system startup, then add one line into /etc/fstab
/$(yourpath)/2440.iso /mnt/2440 iso9660 ro,loop,auto 0 0