Linux Filesystem Hierarchy

symbolic link or soft link
A special filetype, which is a small pointer file, allowing multiple names for the same file. Unlike
hard links, symbolic links can be made for directories and can be made across filesystems. Commands
that access the file being pointed to are said to follow the symbolic link. Commands that access the
link itself do not follow the symbolic link.
system call
The services provided by the kernel to application programs, and the way in which they are invoked.
See section 2 of the manual pages.
system program
Programs that implement high level functionality of an operating system, i.e., things that aren't
directly dependent on the hardware. May sometimes require special privileges to run (e.g., for
delivering electronic mail), but often just commonly thought of as part of the system (e.g., a
compiler).
tcp−wrappers
Almost all of the services provided through inetd are invoked through tcp−wrappers by way of the
tcp−wrappers daemon, tcpd. The tcp−wrappers mechanism provides access control list restrictions
and logging for all service requests to the service it wraps. It may be used for either TCP or TCP
services as long as the services are invoked through a central daemon process such as inetd. These
programs log the client host name of incoming telnet, ftp, rsh, rlogin, finger etc.... requests. Security
options are access control per host, domain and/or service; detection of host name spoofing or host
address spoofing; booby traps to implement an early−warning system.
ZSH
Zsh was developed by Paul Falstad as a replacement for both the Bourne and C shell. It incorporates
features of all the other shells (such as file name completion and a history mechanism) as well as new
capabilities. Zsh is considered similar to the Korn shell. Falstad intended to create in zsh a shell that
would do whatever a programmer might reasonably hope it would do. Zsh is popular with advanced
users. Along with the Korn shell and the C shell, the Bourne shell remains among the three most
widely used and is included with all UNIX systems. The Bourne shell is often considered the best
shell for developing scripts.
Linux Filesystem Hierarchy
Glossary
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