The Berkeley Automounter (or amd) first appeared in 4.4BSD, and is a computer automounter

Automounter

An automounter is any program or software facility which automatically mounts filesystems in response to access operations by user programs. An automounter system utility , when notified of file and directory access attempts under selectively monitored subdirectory trees, dynamically and...

 daemon

Daemon (computing)

In Unix and other multitasking computer operating systems, a daemon is a computer program that runs as a background process, rather than being under the direct control of an interactive user...

. The original Berkeley automounter was created by Jan-Simon Pendry in 1989 and was donated to Berkeley. After languishing for a few years, the maintainership was picked up by Erez Zadok, who has maintained it since 1993.

The am-utils package which comprises amd is included with FreeBSD

FreeBSD

FreeBSD is a free Unix-like operating system descended from AT&T UNIX via BSD UNIX. Although for legal reasons FreeBSD cannot be called “UNIX”, as the direct descendant of BSD UNIX , FreeBSD’s internals and system APIs are UNIX-compliant...

, NetBSD

NetBSD

NetBSD is a freely available open source version of the Berkeley Software Distribution Unix operating system. It was the second open source BSD descendant to be formally released, after 386BSD, and continues to be actively developed. The NetBSD project is primarily focused on high quality design,...

, and OpenBSD

OpenBSD

OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution , a Unix derivative developed at the University of California, Berkeley. It was forked from NetBSD by project leader Theo de Raadt in late 1995...

. It is also included with a vast number of Linux

Linux

Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

 distributions, including Red Hat Enterprise Linux

Red Hat Enterprise Linux

Red Hat Enterprise Linux is a Linux-based operating system developed by Red Hat and targeted toward the commercial market. Red Hat Enterprise Linux is released in server versions for x86, x86-64, Itanium, PowerPC and IBM System z, and desktop versions for x86 and x86-64...

, Fedora Core, ASPLinux, Trustix

Trustix

Trustix Secure Linux was a Linux distribution intended for use on servers and focused on security and stability. It was a hardened and secure OS, meaning that non-essential services and binaries are not installed, while UNIX staples like Sendmail are replaced by programs like Postfix.Trustix was...

, Mandriva

Mandriva

Mandriva S.A. is a publicly traded Linux and open source software company with its headquarters in Paris, France and development center in Curitiba, Brazil. Mandriva, S.A...

, and others.

The Berkeley automounter has a large number of contributors, including several who worked on the original automounter with Jan-Simon Pendry.

It is one of the oldest and more portable automounters available today; it is, arguably, the most flexible and perhaps the most widely used.

Caveats

There are a few "side effects" that come with files that are mounted using automounter. These may differ depending on how the service was configured

• Access time of automounted directories is set to the time automounter was used to mount them (after the directories are accessed, this statistic obviously changes)
• On some systems directories are not visible until the first time they are used. This means commands such as ls will fail
• If mounted directories are not used for a period of time, directories are unmounted
• When automount mount directories they are said to be owned by root until one uses them, at that time the correct owner of the directory shows up

External links

• Am-utils Home Page (home of amd)
• RPMs from rpmfind.net