Extract File(s) From ISO Under Linux OS

Let us assume that your ISO image name is disk1.iso.
Step # 1: First you need to create a directory /mnt/iso

# mkdir /mnt/iso
# mount -o loop disk1.iso /mnt/iso

Step # 2: Extract file
Now you can easily copy file called file.txt from iso disk image to /tmp directory :

# cd /mnt/iso
# cp file.txt /tmp

Step # 3: Copy foo.rpm from ISO disk image:

# cd /mnt/iso/RedHat/RPMS
# cp foo.rpm /tmp