Detecting a chroot jail from within

Question

How can one detect being in a chroot jail without root privileges? Assume a standard BSD or Linux system. The best I came up with was to look at the inode value for \"/\"

Answer 1

The inode for / will always be 2 if it's the root directory of a filesystem, but you may be chrooted inside a complete filesystem. If it's just chroot (and not some other virtualization), you could run mount and compare the mounted filesystems against what you see. Verify that every mount point has inode 2.