The program can take a target encrypted directory on the command line. If unspecified, the utility will search the entire system looking for encrypted private directories, as configured by ecryptfs-setup-private(1).
If an encrypted directory and a wrapped-passphrase file are found, the user is prompted for the login (wrapping) passphrase, the keys are inserted into the keyring, and the data is decrypted and mounted.
If no wrapped-passphrase file is found, the user will be prompted for their mount passphrase. This passphrase is typically 32 characters of [0-9a-f]. All users are prompted to urgently record this randomly generated passphrase when they first setup their encrypted private directory.
The destination mount of the decrypted data is a temporary directory, in the form of /tmp/ecryptfs.XXXXXXXX.
By default, the mount will be read-only. To mount with read and write permission, add the --rw parameter.
http://blog.dustinkirkland.com/2009/03/mounting-your-encrypted-home-from.html
On Debian and Ubuntu systems, the complete text of the GNU General Public License can be found in /usr/share/common-licenses/GPL.