Using /dev/loop to view a CD image

This tip explains how to use the loop device to view or share files from a CD image or ISO file.

First, you need to make sure you have support in your kernel. It can be configured as a module so there's no need to reboot if you don't have support.

Code Listing 1: Installing the kernel module

// configure the following option"
Block Devices
-> <M> Loopback device support

#  make dep && make modules modules_install
#  insmod loop

To view the contents of an iso file, just mount the iso on a loopback device. For example, here we mount gentoo-basic-x86-1.4_rc4.iso to gentoo-1.4_rc4/.

Code Listing 2: Mounting an iso on a loopback device

# mount gentoo-basic-x86-1.4_rc4.iso gentoo-1.4_rc4 -o loop=/dev/loop1,blocksize=1024

Now you can view the directory gentoo-1.4_rc4 just as if it were part of your regular filesystem.

From http://www.gentoo.org/news/en/gwn/20030414-newsletter.xml