U

UDMA

Ultra-DMA - an advanced technology which provides for even faster throughput, up to 33.3 MB/s in UDMA mode 2 and 66.7 MB/s in UDMA mode 4, twice to four times that of EIDE, for much lower prices than SCSI. From Linux Guide @FirstLinux

UDP

User Datagram Protocol - a simple connectionless TCP service. From Linux Guide @FirstLinux

UDP (User Datagram Protocol)

One of the protocols for data transfer that is part of the TCP/IP suite of protocols. UDP is a "stateless" protocol in that UDP makes no provision for acknowledgement of packets received. See also: Packet Switching, TCP/IP. From Matisse

UDP (User Datagram Protocol)

UDP is a transport protocol that provides "datagram" services on top of IP. Contrast: There are two transport protocols: UDP and TCP. Both of these are responsible for hooking up the programs that are communicating with each other, whereas the underlying IP is simply responsible for getting the packets from machine to machine across the Internet. UDP is essentially just a light-weight version of TCP. Whereas TCP will automatically retransmit lost packets, UDP doesn't care. This is actually a benefit for audio/visual, but a severe disadvantage when transferring files. UDP Format: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Port | Destination Port | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ There is nothing to exciting about UDP. The source port identifies the application on the sending machine. The destination port identifies who is to receive the data. The length indicates how much data is in the packet; the checksum verifies that it has not been accidentally altered in transit (though it cannot protect against deliberate alteration). From Hacking-Lexicon

UHU-Linux

UHU-Linux is a Linux distribution from Hungary. It is an easily installable, dpkg-based distribution, with fully automatic hardware detection (based partly on Mandrake and other distros). It is primarily aimed at beginners. Version 1.0 was released April 18, 2003. From LWN Distribution List

UID

Expands to the user ID of the current user, initialized at shell startup. From Rute-Users-Guide

UID

the User ID number of the user that owns this process. From Linux Guide @FirstLinux

UN*X

n. Used to refer to the Unix operating system (a trademark of AT&T, then of Novell, then of Univel, then of the Open Group; the source code parted company with it after Novell and was owned by SCO, which was acquired by Caldera) in writing, but avoiding the need for the ugly (TM) typography. Also used to refer to any or all varieties of Unixoid operating systems. Ironically, lawyers now say that the requirement for the trademark postfix has no legal force, but the asterisk usage is entrenched anyhow. It has been suggested that there may be a psychological connection to practice in certain religions (especially Judaism) in which the name of the deity is never written out in full, e.g., `YHWH' or `G-d' is used. See also glob and splat out. From Jargon Dictionary

UNIX

An operating system used on a wide variety of computers, from mainframes to personal computers, that supports multitasking and is ideally suited to multiuser applications. UNIX is a very flexible operating system, well-suited to the needs of advanced computer users. With more than 200 commands, inadequate error messages, and a cryptic command syntax, however, UNIX imposes heavy burdens on occasional users and the technically unsophisticated. With the development of UNIX shells such as NeXTStep, the operating system may play a much wider role in computing. Because Bell Laboratories was prohibited from marketing UNIX by the antitrust regulations governing AT&T before the 1980s, UNIX was provided without charge to colleges and universities throughout North America. beginning in 1976. In 1979, the University of California at Berkeley developed a popular version of UNIX for VAX computers. In the early 1980S, AT&T gained the right to market the system and released System V in 1983. See Berkeley UNIX System V lnterface Definition (SVID) and Linux, Wide Area Information Server (WAIS). From QUECID

UNIX

Key point: There really is no "UNIX", but just various implementations designed along the same guidelines. Different versions of UNIX are more or less related, and there is extensive cross-germination of ideas, so that something good that appears in one will eventually migrate to others. Contrast: There have been two main branches of UNIX: SVR4 (System V Release 4) and BSD (Berkeley Standard Distribution). Many security issues depend upon which base the system was derived. Example: Sun Solaris, IBM AIX, SCO, SGI Irix, Apple A/UX, BSD, HP/UX. Key point: UNIX is case-sensitive, whereas Windows and Macintosh are "case-insensitive" but "case-preserving". Windows has a compatibility mode that allows case-sensitivity, which can sometimes be exploited with other techniques in order to compromise the system. Key point: The BSD branch has spawned many open-source variants, such as FreeBSD and OpenBSD. OpenBSD is considered one of the more secure versions of UNIX. Security experts spend the most time on OpenBSD in order to clean up bugs like buffer-overflows. However, in 1999, the dramatic rise of hacking and publication of bugs has led to a heightened awareness of these problems, which may lead to other systems becoming equally scoured for bugs. How to: In order to harden UNIX, you generally do the following: Always start from a fresh machine newly installed. When installing, do not install any options that aren't absolutely necessary. Many people are unsure if an option is needed, so they install it just to be sure. Do the opposite (don't install it in order to make sure you don't introduce a backdoor). After installation, remove all unnecessary software; anything with an X Windows GUI is a good start. Cleanse /etc/inetd.conf of all unnecessary services. For any server connected to the Internet, pretty much everything in there will be unnecessary. Install a Tripwire-style package to detect when system files have changed (i.e. binaries in /sbin and configuration files in /etc). This doesn't secure the system, but it helps in detecting when intrusions have occurred. Note that this program is difficult to get running and maintain over the long term. Install TCP Wrappers to log connections and provide some limited access control. Shadow /etc/passwd. Remove all entries for disabled services and set a dummy shell for those accounts that shouldn't have shell access. Redirect syslog to a secure system or drop-box. Get rid of Telnet, use ssh. Plan to do all remote administration and file copies through ssh. If you are extremely paranoid, put binaries on a CD-ROM. Some versions of open source UNIXes can even boot from CD-ROMs. Install packet filtering software. Install network intrusion detection software. Key point: Typical UNIX weaknesses are: default passwords weak (guessable, crackable) passwords NIS misconfigurations NFS holes incorrect permissions race conditions (esp. in /tmp) exploitable SUID programs sendmail problems UPS (Uninterruptible Power Supply) [2] A UPS continues to provide electricity to equipment in the case of a power failure. Much of security contains flawed policies for fail-open/fail-close. By causing devices to fail (such as cutting their power), an intruder may be provided access. For example, electronic doors will automatically open in cases of power failures in order to prevent people from getting trapped. Likewise, some firewalls are configured with bypasses that will allow access in cases of power failure to the firewall. Key point: The MTBF of the average UPS is five to ten years. High-end colos attempt to provide power grids that exceed this. Key point: Increasingly, UPS units are being given interfaces for network management. This allows them to be hacked and have their power interrupted. From Hacking-Lexicon

UNIX

UNIX began as a proprietary operating system developed by Bell Laboratories in the 1960s. It eventually spawned a number of mutually incompatible commercial versions from such companies as Apple (Mac OS X), Digital (Digital UNIX), Hewlett-Packard (HPUX), IBM (AIX.), NeXT (NeXTSTEP) and others. From I-gloss

UNIX

UNIX is an operating system commonly used on Workstations, and multi-user larger systems. It is a very powerful operating system for administering many users, multi-tasking and communications and has played a major role in the development of the Internet - it is the preferred operating system for host Internet connections (World Wide Web, email servers, and specialist hardware such as routers). From Faculty-of-Education

UNIX-to-UNIX Copy Program (UUCP)

A network, based on long-distance telephone uploads and downloads. UUCP allows UNIX users to exchange files, electronic mail and Usenet articles. In the 1980s, when Internet connectivity was hard to come by, UUCP played an important role in providing support for the UNIX operating system. From QUECID

URL

A Uniform Resource Locator is basically the address of any resource on the Internet. You type the URL in your browser and you are whizzed off to the appropriate site. e.g. http://ole.net/ole/ From Glossary of Distance Education and Internet Terminology

URL

An acronym for Uniform Resource Locator, URL's are a standardized format for giving a pointer to information available from... A Primer explaining the use of URL's is available. From KADOWKEV

URL

Uniform Resource Locator: a standardized format for giving a pointer to information available from gopher,WWW, finger and other servers. From Linux Guide @FirstLinux

URL encoding (application/form-url-encoded)

A problem exists when people need to send binary data as part of a URL. Therefore, URLs include the ability to "encode" binary information as part of the text field. Key point: This encoding mechanism can be used to alter the signature of a hacker attack via web-based protocols. Such encoding can be used to evade detection by lightweight intrusion detection systems that are unable to "normalize" the URL. Example: The Microsoft web-server in their ASP server-side scripts such that a hacker could append a dot to the end of the URL in order to read the script contents rather than executing the script. Microsoft created a patch, but hackers soon found they could evade the patch by URL-encoding the dot (appending a %2E to the end of the scrip rather than a dot). Examples: http://www.robertgraham.com/sample.asp Normal URL http://www.robertgraham.com/sample.asp. Attempt to read script rather than executing it. http://www.robertgraham.com/sample.asp%2E URL-encoding in order to evade patch. http://www.robertgraham.com/sample.%61sp%2E Further URL-encoding in order to evade intrusion detection systems. From Hacking-Lexicon

USENET

A world-wide system of discussion groups, with comments passed among hundreds of thousands of machines. Not all USENET machines are on the Internet. USENET is completely decentralized, with over 10,000 discussion areas, called newsgroups. From Matisse

USENET

Point: The protocol for transporting USENET messages is called NNTP: "Network News Transport Protocol". Key point: The USENET Death Penalty (http://www.stopspam.org/usenet/faqs/udp.html) is often applied to NNTP servers in order to stop the flood of spam. It is often applied to ISPs who allow users to send lots of spam or allow their servers to be hijacked. For this reasons, many ISPs (especially high-speed cable modem and DSL providers will scan their customers looking for unauthorized NNTP servers. Controversy: USENET presents a philosophical challenge to the Internet because of its distributed nature. It allows anonymous publishing of material that cannot be traced back to the source. This challenges the historic concepts of intellectual property and how it can be protected. For example, when RC2 and RC4 were posted to USENET, they stopped being trade-secrets. From Hacking-Lexicon

USENET

USEr NETwork: a public access network on the Internet that provides user news. There are a number of newsgroups dedicated to Linux issues including the moderated comp.os.linux.announce for Linux announcements. From Linux Guide @FirstLinux

UUCP

A set of programs and protocols that have become the basis for a worldwide network of UNIX computers. Named after the UNIX to UNIX Copy Program. From I-gloss

UUCP

A set of programs and protocols that have become the basis of a worldwide network between UNIX systems; named after the UNIX-to-UNIX copy program. From Linux Guide @FirstLinux

UUCP

An acronym for Unix to Unix CoPy, UUCP is a protocol used for the store-and-forward exchange of mail, Usenet News and other files, usually over a modem. From KADOWKEV

UUCPNET

n. obs. The store-and-forward network consisting of all the world's connected Unix machines (and others running some clone of the UUCP (Unix-to-Unix CoPy) software). Any machine reachable only via a bang path is on UUCPNET. This term has been rendered obsolescent by the spread of cheap Internet connections in the 1990s; the few remaining UUCP links are essentially slow channels to the Internet rather than an autonomous network. See network address. From Jargon Dictionary

UUENCODE (Unix to Unix Encoding)

A method for converting files from Binaryto ASCII (text) so that they can be sent across the Internet via email. From Matisse

UUEncode

A popular method of exchanging binary files in Mail and via Usenet News the uuencode program converts a binary file into a (larger) file of alphanumeric characters that will not be corrupted when sent as a text file. UUEncode is available as a Unix command as well as MS-DOS and Macintosh versions. To convert the file back to the original binary form you can use the uudecode program or the popular Unix extraction program uuconvert. From KADOWKEV

UUencode/UUdecode

The 'UU' part refers to 'Unix to Unix' - the most common host to host connection on the Internet. The 'encode/decode' part refers to a standard for converting non-ASCII data transmission via email. From Faculty-of-Education

UUencoding

A method of converting binary files to ASCII so they can be sent to other Internet users. The uuencode program converts the binary file to ASCII, and the uudecode program returns the file to its original form. From Linux Guide @FirstLinux

UltraLinux

UltraLinux is one of the first, if not the first, port of Linux to the SPARC family of processors most commonly found in Sun workstations and clones. It supports most workstations including the older 32bit SPARC processors and the newer 64bit UltraSPARC based workstations. From LWN Distribution List

Unicode

The international character set. The United States characters ASCII only needs 7-bits to encode text. There are fewer than 100 characters in the English language (26-upper-case, 26-lower-case, 10-digits, and a bunch of punctuation). Since 7-bits has 128 combinations, it is sufficient to cover the characerts plus a few control codes. However, there are other alphabets, such as Russian, Greek, and Hebrew. Even worse, far-eastern languages like Chinese, Japanese, and Korean use symbols/ideographs to represent words without a strict alphabet. The Unicode character set was built to represent all these characters within a 2-byte (16-bit) format. Roughly 30,000 characters from all the popular languages have been assigned in an internationally agreed upon format. Key point: Most computers are built to handle 1-byte characters, and do not like the idea of handling 2-bytes for each character. Therefore, a multi-byte character set has been designed to store Unicode. It is called "UTF8". It is the native character set for many newer systems, such as Java. Using "multibyte" rather than "fixed" character set means that a variable number of bytes can be used, depending upon how many bytes/bits are needed to represent the character. The key issue here is that every 7-bit ASCII character can be encoded in all forms. For example, older Microsoft IIS web-servers would check for backtracking attacks. However, a UTF8 encoding of the backtracks would bypass the IIS checks, but would still be passed to the filesystem. Encoding Bits Encoding of '.' 0xxxxxxx 7-bits 2E 110xxxxx 10xxxxxx 11-bits C0 AE 1110xxxx 10xxxxxx 10xxxxxx 15-bits E0 80 AE See also: encoding From Hacking-Lexicon

Uniform Resource Identifier (URI)

A tring of characters that identifies an Internet resource, including the type of resource and its location. There are two types of URIs: Uniform Resource Locators (URLs) and Relative URKS (REL URQ). From QUECID

Uniform Resource Locator (URL)

One of two basic kinds of Universal Resource Identifiers (URI), a string of characters that precisely identifies an Internet resource's type and location. For example, the following fictitious URL identifies a World Wide Web document (http : / /), indicates the domain name of the computer on which it is stored (www.wolverine. virginia .eau), fully describes the document's location within the directory structure (~toros/winerefs/), and includes the document's name and extension (merlot.html). http://www.wolverine.virglnia.edu/~toros/winerefs/merlot.html See Relative URL (RELURL). From QUECID

Uninterruptible poewr supply (UPS)

A battery that can supply continuous power to a computer system in the event of a power failure. The battery, charged while your computer is swtiched on, kicks in if the power fails and provides power for 10 minutes or more, during which time you can save fils and shut down the computer to preserve the integrity of crucial data. From QUECID

Unix

/yoo'niks/ n. [In the authors' words, "A weak pun on Multics"; very early on it was `UNICS'] (also `UNIX') An interactive time-sharing system invented in 1969 by Ken Thompson after Bell Labs left the Multics project, originally so he could play games on his scavenged PDP-7. Dennis Ritchie, the inventor of C, is considered a co-author of the system. The turning point in Unix's history came when it was reimplemented almost entirely in C during 1972-1974, making it the first source-portable OS. Unix subsequently underwent mutations and expansions at the hands of many different people, resulting in a uniquely flexible and developer-friendly environment. By 1991, Unix had become the most widely used multiuser general-purpose operating system in the world - and since 1996 the variiant called Linux has been at the cutting edge of the open source movement. Many people consider the success of Unix the most important victory yet of hackerdom over industry opposition (but see Unix weenie and Unix conspiracy for an opposing point of view). See Version 7, BSD, USG Unix, Linux. Some people are confused over whether this word is appropriately `UNIX' or `Unix'; both forms are common, and used interchangeably. Dennis Ritchie says that the `UNIX' spelling originally happened in CACM's 1974 paper "The UNIX Time-Sharing System" because "we had a new typesetter and troff had just been invented and we were intoxicated by being able to produce small caps." Later, dmr tried to get the spelling changed to `Unix' in a couple of Bell Labs papers, on the grounds that the word is not acronymic. He failed, and eventually (his words) "wimped out" on the issue. So, while the trademark today is `UNIX', both capitalizations are grounded in ancient usage; the Jargon File uses `Unix' in deference to dmr's wishes. From Jargon Dictionary

Unix

A computer operating system (the basic software running on a computer, underneath things like word processors and spreadsheets). Unix is designed to be used by many people at the same time (it is multi-user) and has TCP/IP built-in. It is the most common operating system for servers on the Internet. Apple computers' Macintosh operating system, as of version 10, is based on Unix. From Matisse

Unix

A computer operating system commonly used on the Internet. Uplink: The communication link from the transmitting earth station to the satellite. From Glossary of Distance Education and Internet Terminology

Upload

Transferring data (usually a file) from a the computer you are using to another computer. The opposite of download. From Matisse

UseNet

The leading distributed bulletin board, widely available on UNIX-based computer systems, and linked through the Internet and other computer networks. Offering more than 1,500 newsgroups, UseNet is accessed daily by more than 15 million people in more than 100 countries. Within UseNet is a discussion group (newsgroup) on every conceivable topic and some you haven't thought of. Each newsgroup focuses on a particular subject, such as sports cars, firearms, U.S. history, model aircraft, politics, or jazz. Well-represented subjects are hobbies, politics, scientific disciplines, and topics of current public debate. UseNet users can read and reply to posted messages. From QUECID

Usenet

Usenet is derived from "User's Network" and was originally a separate service, or what is called a Bulletin Board System. It is very developed but is seldom called Usenet now -- more commonly referred to as newsgroups, discussion groups, or sometimes just News. There are no restrictions on joining a newsgroup. While not all Usenet machines are on the Internet, this is rapidly changing. There are over 10,000 newsgroups. URL's for newsgroups differ in appearance, with no domain name appearing -- eg., news:comp.jobs.offered From Faculty-of-Education

Usenet News

A network of systems that exchange articles using the Internet, UUCP, and other methods to establish public message conferences on some or all of over 6,000 topics or "newsgroups. There are many common newsgroups include some that can run on your home computer via SLIP and the Unix newsreaders, tin, trn, and nn. From KADOWKEV

Usenet Newsgroups

More than 10,000 topic-oriented message bases that can be read and posted to. Also called newsgroups, please visit at http://www.dejanews.com/ From Glossary of Distance Education and Internet Terminology

User Accounts and User Ownerships

UNIX intrinsically supports multiple users. Each user has a personal home directory /home/<username> in which the user's files are stored, hidden from other users. So far you may have been using the machine as the root user, who is the system administrator and has complete access to every file on the system. The root is also called the superuser. The home directory of the root user is /root. Note that there is an ambiguity here: the root directory is the topmost directory, known as the / directory. The root user's home directory is /root and is called the home directory of root. Other than the superuser, every other user has limited access to files and directories. Always use your machine as a normal user. Log in as root only to do system administration. This practice will save you from the destructive power that the root user has. In this chapter we show how to manually and automatically create new users. Users are also divided into sets, called groups. A user can belong to several groups and there can be as many groups on the system as you like. Each group is defined by a list of users that are part of that set. In addition, each user may have a group of the same name (as the user's login name), to which only that user belongs. From Rute-Users-Guide

Uudecode

A UNIX ultility program that decodes a uuencoded ASCII file, restoring the original binary file (such as a program or graphic) A uudecode utility is needed to decode the binary files posted to UseNet Programs with uudecoding capabilities are avaiable for Macintosh and Microsoft Windows 95 systems, and are often built into UseNet newsreaders. From QUECID

Uuencode

A UNlX utility program that transforms a binary file such as a program or graphic, into coded ASCII text. This text can be transferred by means of the Internet or posted to a UseNet newsgroup At the receiving end, the uudecode utility decodes the message and restores the binary file. Programs with uuencoding capabilities are available for Macintosh and Microsoft Windows 95 systems, and are often built into UseNet newsreaders. From QUECID

uClibcLinux

uClibcLinux is a Linux distribution based on uClibc. This source-based distribution has two main goals: - provide an easily extensible build-system - provide a repository of software compiling and running with uClibc. Initial version 0.4.5 was released June, 25, 2002. From LWN Distribution List

uClinux

The Linux/Microcontroller project is a port of Linux to systems without a Memory Management Unit (MMU). Pronounced "you-see-linux", the name uClinux comes from combining the greek letter "mu" and the english capital "C". "Mu" stands for "micro", and the "C" is for "controller". uClinux was first ported to the Motorola MC68328: DragonBall Integrated Microprocessor. The first target system to successfully boot is the 3Com PalmPilot using a TRG SuperPilot Board with a custom boot-loader created specifically for our Linux/PalmPilot port. Version 20020701 was initially released on Freshmeat on July 16, 2002. Version 2.4.20-uc0 was released December 4, 2002. Version 2.5.69-uc0 was released May 5, 2003. Version 20030522 was released May 24, 2003. From LWN Distribution List

uOS

uOS is a complete source based Operating System that can be configured and built in a flexible way. uOS was first used in November 2002. It is very new and there are lots of kinks to work out. Although the goal is to make uOS usable by everyeone it currently requires Unix expertise to install and to run. uOS is based on GCC 3.2 / GLIBC 2.3 / WOLK Linux Kernel / X 4.2.1. It supports the newest drivers as well as the newest compilers. Core components are available under the 4F Licensing system (compliant to DFSG and OSI guidelines for Free Software). Initial version 0.81 was released November 6, 2002. From LWN Distribution List

uae

The Ubiquitous Amiga Emulator: Base UAE is a 100% software Amiga (500) hardware emulator. This is the base package including all support files and the most common binary of UAE for X. NOTE: For "proper" use of UAE, you need some version of the Kickstart ROM, and some OS running on top of this (most likely some version of the Amiga OS). Both don't comply to the DFSG (to say the least) and must be obtained from other sources. There is information in the package docs how to obtain these if you are owner of an Amiga box. However, there is a minimal free build-in Kickstart replacement, and at least some demo disks are reported to run with it. From Debian 3.0r0 APT

uae-exotic

The Ubiquitous Amiga Emulator: Exotic binaries UAE is a 100% software Amiga (500) hardware emulator. This package contains binaries of UAE with "exotic" display modes. From Debian 3.0r0 APT

uae-suid

The Ubiquitous Amiga Emulator: Suid root binaries UAE is a 100% software Amiga (500) hardware emulator. This package contains binaries of UAE with display modes that require root privileges (i.e. SVGA and X-DGA versions). These binaries are often considered to be a little bit faster, however this very much depends on your hardware. I (and the upstream authors) DON'T RECOMMEND INSTALLING THESE BINARIES (for the usual security problems) unless you have good reasons for it. From Debian 3.0r0 APT

ubh

Download and decode Usenet binaries UBH (Usenet Binary Harvester) is a Perl console application which automatically discovers, downloads, and decodes single- and multi-part Usenet binaries. UBH provides searching via Perl regular expression and a pre-selection capability whereby the user can interactively choose which binaries to download. From Debian 3.0r0 APT

ucblogo

a dialect of lisp using turtle graphics famous for teaching kids. From whatis

ucblogo

a dialect of lisp using turtle graphics famous for teaching kids. This is the UC Berkeley implementation of logo written primarily by Daniel Van Blerkom, Brian Harvey, Michael Katz, and Douglas Orleans. This version of logo is featured in Brian Harvey's book _Computer_Science_Logo_Style, _Volume_1: _Symbolic_Computing_ (ISBN 0-262-58151-5). This version provides the following special features: - Random-access arrays. - Variable number of inputs to user-defined procedures. - Mutators for list structure (dangerous). - Pause on error, and other improvements to error handling. - Comments and continuation lines; formatting is preserved when procedure definitions are saved or edited. - Terrapin-style tokenization (e.g., [2+3] is a list with one member) but LCSI-style syntax (no special forms except TO). The best of both worlds. - First-class instruction and expression templates. - Macros. From Debian 3.0r0 APT

ucf

Update Configuration File - preserve user changes in config files Debian policy states that configuration files must preserve user changes during package upgrade. The easy way to achieve this behavior is to make the configuration file a `conffile', in which case dpkg handles the file specially during upgrades, prompting the user as needed. This is appropriate only if it is possible to distribute a default version that will work for most installations, although some system administrators may choose to modify it. This implies that the default version will be part of the package distribution, and must not be modified by the maintainer scripts during installation (or at any other time). This script attempts to provide conffile like handling for files that can not be labelled conffiles, are not shipped in a Debian package, but handled by the postinst instead. This script allows one to maintain files in /etc, preserving user changes and in general offering the same facilities while upgrading that dpkg normally provides for "conffiles". Additionally, this script provides facilities for transitioning a file that had not been provided conffile like protection to come under this schema, and attempts to minimize questions asked at install time. Indeed, the transitioning facility is better than the one offered by dpkg while transitioning a file from a non-conffile to conffile status. From Debian 3.0r0 APT

uclibc-toolchain

A compiler wrapper for uClibc This package includes utilities that function as a toolchain for compiling with uClibc instead of the native libc. The utilities have names such as powerpc-uclibc-gcc (depending on the architecture), and should behave identically to the base utilities, except that they use headers and libraries provided in the libuclibc-dev package. Most utilities are symbolic links to the correct underlying utility, although gcc and ld are implemented as wrapper binaries that call gcc and ld with the necessary arguments and command line options. From Debian 3.0r0 APT

ucs2any

generate BDF fonts containing subsets of ISO 10646-1 codepoints From whatis

ucspi-proxy

Connection proxy for UCSPI tools This package contains a proxy program that passes data back and forth between two connections set up by a UCSPI server and a UCSPI client. See http://cr.yp.to/proto/ucspi.txt for more information on UCSPI. See http://em.ca/~bruceg/ucspi-proxy/ for recent informations. From Debian 3.0r0 APT

ucspi-unix

UNIX-domain socket client-server command-line tools unixclient and unixserver are command-line tools for building UNIX domain client-server applications. unixclient connects to a UNIX domain socket and runs a program of your choice. unixserver creates a UNIX domain socket, waits for incoming connections and, for each connection, runs a program of your choice. unixclient and unixserver conform to UCSPI, the UNIX Client-Server Program Interface, using UNIX domain sockets. UCSPI tools are available for several different networks. See http://cr.yp.to/proto/ucspi.txt for more information on UCSPI. See http://em.ca/~bruceg/ucspi-unix/ for recent informations. From Debian 3.0r0 APT

ud

Uptime Daemon UD runs in the background constantly checking the current uptime against your 3 best uptime records. If the current uptime surpasses a record, that becomes the new record. By using a template UD can create HTML files that shows the current uptime records. The HTML files are updated by the daemon. From Debian 3.0r0 APT

ude

The Unix Desktop Environment UDE is more then just another windows manager. Designed to compensate for the shortcomings of many other similar packages, UDE features many innovative improvements. The project does not use any special GUI-Libraries such as Qt or GTK+ and is based on the standard Xlibs (also to make UDE faster) UDE - get used to it. From Debian 3.0r0 APT

udftools

Tools for UDF filesystems and DVD/CD-R(W) drives This package contains a number of user-space tools related to creating filesystems in the UDF (Universal Disk Format), which is primarily used for DVDs, but sometimes also CD-ROMs: mkudffs - Format a device, creating an empty UDF filesystem cdrwtool - Low-level drive management (e.g. set writing speed, format) pktsetup - Set up a packet writing device (/dev/pktcdvd0) for a drive Note that you need Linux 2.4 or later to mount UDF filesystems. The kernel patches that accompany these tools are not currently packaged for Debian, but are being merged into the 2.4 kernel tree. From Debian 3.0r0 APT

udhcpc

very small DHCP client This is the very small DHCP client written by Moreton Bay/Lineo. From Debian 3.0r0 APT

udhcpd

very small DHCP server This is the very small DHCP server written by Moreton Bay/Lineo. From Debian 3.0r0 APT

ugidd

NFS UID mapping daemon. This package contains the UID mapping daemon (rpc.ugidd) which is used on NFS clients to do UID/GID mapping. From Debian 3.0r0 APT

ui-properties

allows you to change certain Gnome user interface. From whatis

uic

Qt ui compiler This package contains the Qt ui compiler. It is needed to build more and more Qt based applications. There are 2 versions of this binary, one with KDE widget support and one without. This one is compiled without. From Debian 3.0r0 APT

uisp

Micro In-System Programmer for Atmel's AVR MCUs This utility is required to program AVR chips with object code created by the ava assembler/linker. It supports in-system programming, Atmel's prototype board/programmer, and an extremely low-cost parallel port programmer. From Debian 3.0r0 APT

ul

do underlining From whatis

ulogd

The Userspace Logging Daemon ulogd is a daemon that listens for Netlink packets generated by iptables's ULOG target. Basically, it's a replacement for syslog for logging packets, and does a much better job - it logs to files, mySQL, and soon will be able to log remotely. mySQL support is in a separate package, called ulogd-mysql. The relevant kernel support is included in a patch - kernel-patch-ulog. ulogd homepage: http://www.gnumonks.org/projects/ulogd From Debian 3.0r0 APT

ulogd-mysql

mySQL extension to ulogd This extension adds mySQL support to ulogd; please see ulogd's description. description. From Debian 3.0r0 APT

ultrapoint

A GGI based presentation tool UltraPoint is a simple, XML based presentation program designed to help aid with instant preparation. (This does not measn 'easy to use this program') As compared with most of the existing tools, UltraPoint requires no special adjustment cost (e.g. positions of objects). -- Features . Drawing with GGI (General Graphics Interface) . Accessing a lot of font formats with VFlib 3.6. . Arranging scaled images with ImageMagick. From Debian 3.0r0 APT

umb-scheme

UMB Scheme is a public domain implementation of the Scheme programming language. Scheme is a statically scoped and properly tail-recursive dialect of the Lisp programming language, designed with clear and simple semantics and a minimal number of ways to form expressions. Install the umb-scheme package if you need an implementation of the Scheme programming language. From Mandrake 9.0 RPM

umfpack3

Set of routines for solving unsymmetric sparse linear systems. UMFPACK is a set of routines for solving unsymmetric sparse linear systems, Ax=b, using the Unsymmetric MultiFrontal method. Written in ANSI/ISO C, with a Matlab (Version 6.0 and later) interface. The new code is faster than V2.2.1, uses dynamic memory allocation, and has a symbolic preordering and analysis phase that also reports the upper bounds on the nonzeros in L and U, flop count, and memory usage in the numeric phase. It includes a Matlab interface. V3.2 is for double-precision matrices only (not complex). From Debian 3.0r0 APT

uml-utilities

User-mode Linux (utility programs) User-mode Linux is a port of the Linux kernel to its own system call interface. It provides a kind of virtual machine, which runs Linux as a user process under another Linux kernel. This is useful for kernel development, sandboxing, jailing, experimentation, and many other things. This package contains userspace utilities for use with User-mode Linux, including uml_mconsole, uml_moo, uml_switch, uml_net and tunctl. From Debian 3.0r0 APT

umodpack

Installer and viewer for .umod-files (Unreal Mod files) UmodPack is a crossplatform tool for umod installation and unpacking. umod files are packages containing files with setup instructions for an Unreal mod (modification). For more information on Unreal mods in general see <http://www.planetunreal.com/modcentral/> From Debian 3.0r0 APT

umount

mount and unmount filesystems. From whatis

umount

unmount file systems From whatis

umsdos

This is the distribution of the UMSDOS file system utilities. With the kernel configured accordingly these utilities allow the usage of of Unix filesystem feature on top of the MSDOS filesystem. It is even possible to run Linux completely on an MSDOS formatted disk without repartitioning or reformatting. From Debian 3.0r0 APT

unaccent

Replace accented letters by their unaccented equivalent read data from stdin, replace accented letters by their unaccented equivalent and write the result on stdout. From Debian 3.0r0 APT

uname

A UNIX command that returns a description of the current operating system. It describes the machine hardware type (e.g. Pentium), the name of the node on the network, which release of the OS, the OS name, specific CPU information, and the version of the OS. Key point: This is often the first command a hacker will run on the system when the hacker breaks in remotely. Hackers rarely known exactly what kind of system they have attacked. The other popular command hackers might execute is id. Example: Running uname -a on one of my systems results in: Linux gandalf.robertgraham.com 2.2.13-4mdk #1 Tue Sep 7 18:23:11 CEST 1999 i686 unknown From Hacking-Lexicon

uname

get name and information about current kernel From whatis

uname

print system information From whatis

unclutter

hides the mouse in X after a period of inactivity unclutter is a program which runs permanently in the background of an X session. It checks on the X mouse pointer position every few seconds, and when it finds it has not moved (and no buttons are pressed on the mouse, and the cursor is not in the root window) it hides the mouse cursor. It restores the mouse cursor when the mouse is moved or when a mouse button is hit. From Debian 3.0r0 APT

uncompress

compress or expand files From whatis

unexpand

convert spaces to tabs From whatis

unhtml

Removing the markup tags from a HTML file This program removes all HTML tags from a HTML file and directs it's output to stdout. It can be used as a filter for getting the text content of a HTML file without the need of firing up a web browser. From Debian 3.0r0 APT

unicast

a type of communication between hosts (or computers) on a network where a host talks directly to another computer. See broadcast and multicast. From Linux Guide @FirstLinux

unicode_start

put the console in Unicode mode. From whatis

unicode_stop

put the console out of unicode mode (ie. in 8-bit mode). From whatis

unicon-im

Chinese Input Method Libaray General Chinese Input method interface and API. It is using by chinput and unicon now. From Debian 3.0r0 APT

unifont

X11 dual-width GNU unicode font The GNU unicode font is an X11 bitmap font in iso10646 encoding. It is useful if you have X programs such as the yudit text editor that are unicode aware. From Debian 3.0r0 APT

uninterruptible power supply (UPS)

A battery that can supply continuous power to a computer system in the event of a power failure. The battery charged while your computer is switched on, kicks in if the power fails and provides power for 10 minutes or more, during which time you can save files and shut down the computer to preserve the integrity of crucial data. From QUECID

uniq

remove duplicate lines from a sorted file From whatis

unison

A file-synchronization tool for Unix and Windows Unison is a file-synchronization tool for Unix and Windows, written in OCaml. It allows two replicas of a collection of files and directories to be stored on different hosts (or different disks on the same host), modified separately, and then brought up to date by propagating the changes in each replica to the other. Unison offers several advantages over various synchronization methods such as CVS, Coda, rsync, Intellisync, etc. Unison can run on and synchronize between Windows and many UNIX platforms. Unison requires no root privileges, system access or kernel changes to function. Unison can synchronize changes to files and directories in both directions, on the same machine, or across a network using ssh or a direct socket connection. Transfers are optimised using a version of the rsync protocol, making it ideal for slower links. Unison has a clear and precise specification, and is resilient to failure due to its careful handling of the replicas and its private structures. From Debian 3.0r0 APT

unison-gtk

A file-synchronization tool for Unix and Windows - GTK interface This package adds the optional GTK interface to the file synchronization tool 'unison'. From Debian 3.0r0 APT

units

converts between different systems of units. GNU 'units' program converts quantities expressed in various scales to their equivalents in other scales. The 'units' program can only handle multiplicative scale changes. For example, it cannot convert Celsius to Fahrenheit but it can convert temperature differences between those temperature scales. From Debian 3.0r0 APT

unix2dos

A utility that converts plain text files in UNIX format to DOS format. From Redhat 8.0 RPM

unix_chkpwd

check the password of the invoking user From whatis

unixcw

Shared library for Morse programs Package needed by unixcw, cwcp and xcwcp. It contains a shared library with Morse code functions. From Debian 3.0r0 APT

unixodbc

ODBC tools libraries Binaries and libraries from the unixODBC package. COMPONENTS: libodbc.so (ODBC Driver Manager) libodbctxt.so (driver for Text files) dltest (simple cmd line tool) isql (cmd line tool... batch & interactive SQL) Driver Template (a template for Driver programmers) From Debian 3.0r0 APT

unixodbc-bin

Qt-based GUI ODBC tools Qt-based GUI Binaries from the unixODBC package. ODBCConfig (GUI Setup using libodbcinst.so) DataManager (GUI to explore ODBC Data Sources) From Debian 3.0r0 APT

unlink

delete a name and possibly the file it refers to From whatis

unlink

unlink a file From whatis

unrtf

RTF to other formats converter UnRTF is a moderately complicated converter from RTF to other formats, including HTML, LaTeX, text, and PostScript. Converting to HTML, it supports tables, fonts, colors, embedded images, hyperlinks, paragraph alignment among other things. All other conversions are "alpha"--just begun. From Debian 3.0r0 APT

unshar

unpack a shar file From whatis

unsq

squeeze a sorted word list unsq - unsqueeze a sorted word list From whatis

untex

Remove LaTeX commands from input. Remove LaTeX commands from input and send it to output. From Debian 3.0r0 APT

untrigraph

remove trigraphs from C source code From whatis

unzip

De-archiver for .zip files InfoZIP's unzip program. With the exception of multi-volume archives (ie, .ZIP files that are split across several disks using PKZIP's /& option), this can handle any file produced either by PKZIP, or the corresponding InfoZIP zip program. This version supports encryption. From Debian 3.0r0 APT

unzip

The unzip utility is used to list, test, or extract files from a zip archive. Zip archives are commonly found on MS-DOS systems. The zip utility, included in the zip package, creates zip archives. Zip and unzip are both compatible with archives created by PKWARE(R)'s PKZIPfor MS-DOS, but the programs' options and default behaviors do differ in some respects. From Redhat 8.0 RPM

unzip

list, test and extract compressed files in a ZIP archive From whatis

unzip-crypt

Legacy package for unzip-crypt that you should remove. This package exists only to provide a smooth upgrade from the old unzip-crypt to the new unzip. Please remove it. From Debian 3.0r0 APT

unzipsfx

self-extracting stub for prepending to ZIP archives From whatis

up2date

The Red Hat Update Agent that automatically queries the Red Hat Network servers and determines which packages need to be updated on your machine. From Redhat 8.0 RPM

update

daemon to periodically flush filesystem buffers. The update daemon flushes the filesystem buffers at regular intervals. This version does not spawn a bdflush daemon, as this is now done by the kernel's kupdate thread. This package is not needed with Linux 2.2.8 and above. If you do not plan to run a 2.0.x series kernel on this system, you can safely remove this package. update may still be useful in sync mode (as opposed to flush mode) on more recent kernels for the extra paranoid. From Debian 3.0r0 APT

update-alternatives

maintain symbolic links determining default commands From whatis

update-catalog

create or update entry in SGML catalog file From whatis

update-cluster

System to update configuration files for clusters automatically A management system to maintain a systemwide template configuration, update-cluster allows for uniform configuration of several cluster-oriented software. NOTE: Using this package may result in automatically overwriting important configuration files. Be careful. From Debian 3.0r0 APT

update-cluster-hosts

System to update configuration files for clusters automatically A management system to maintain a systemwide template configuration, update-cluster allows for uniform configuration of several cluster-oriented software. This is a module used to configure /etc/hosts using update-cluster infrastructure. From Debian 3.0r0 APT

update-fonts-alias

compile fonts.alias files From whatis

update-fonts-dir

compile fonts.dir files From whatis

update-fonts-scale

compile fonts.scale files From whatis

update-inetd

create, remove, enable or disable entry in /etc/inetd.conf From whatis

update-ispell-dictionary

Bash script to select a new ispell default dictionary. From whatis

update-menus

generate Debian menu system From whatis

update-mime

create or update MIME information From whatis

update-modules

(re)generate /etc/modules.conf and /etc/chandev.conf From whatis

update-passwd

safely update /etc/passwd, /etc/shadow and /etc/group From whatis

update-rc.d

install and remove System-V style init script links From whatis

update-xpdfrc

program to generate xpdf's configuration file From whatis

updatedb

update a file name database From whatis

uprecords-cgi

A CGI script to show the world your highest uptimes This CGI script shows your highest uptimes from the uptimed database. From Debian 3.0r0 APT

upsd

UPS Monitor Program Upsd is a UPS monitor program. It supports both local monitoring of a UPS that is directly connected to the computer's serial port and remote monitoring over a network. Remote monitoring is done by polling the master upsd (the one with the direct serial connection to the UPS). There are a number of options to control the poll interval and the delay before shutdown. From Debian 3.0r0 APT

uptime

Tell how long the system has been running. From whatis

uptime-applet

Gnome applet that displays your system uptime. Just a small gnome applet which displays how long your system has been running. It is made for use with gnome panel. From Debian 3.0r0 APT

uptimed

Utility to track your highest uptimes Uptimed allows you to track your highest uptimes via boot IDs. Features: - Console program to display statistics - Can send mail if a milestone or a new record is reached From Debian 3.0r0 APT

upx-ucl

an efficient live-compressor for executables UPX is an advanced executable file compressor. UPX will typically reduce the file size of programs and DLLs by around 50%-70%, thus reducing disk space, network load times, download times etc. The current version can compress executables for DOS, Linux/ELF (i386 only!) and some other files for different OS. NOTE: This package is based on the UCL library, which is licensed under GPL. From Debian 3.0r0 APT

uqwk

Offline mail and news package creator (NNTP version). Uqwk is a program which collects all of a user's unread mail or news and formats it into a packet for offline reading. QWK, Simple Offline Usenet Packet (SOUP), and ZipNews packet formats are supported. Uqwk also accepts reply packets, so replies can be mailed or posted, depending whether the message is marked private (email) or public (news). Uqwk also supports a small offline command language, so the contents of the user's .newsrc file can be viewed and manipulated offline. This version accesses newsgroups via NNTP. From Debian 3.0r0 APT

uqwk-spool

Offline mail and news package creator (spool version). Uqwk is a program which collects all of a user's unread mail or news and formats it into a packet for offline reading. QWK, Simple Offline Usenet Packet (SOUP), and ZipNews packet formats are supported. Uqwk also accepts reply packets, so replies can be mailed or posted, depending whether the message is marked private (email) or public (news). Uqwk also supports a small offline command language, so the contents of the user's .newsrc file can be viewed and manipulated offline. This version accesses newsgroups via a local news spool. From Debian 3.0r0 APT

url-properties

determine which browser is responsible for various types of URLs. From whatis

urlredir

utility for squid to perform url redirection. This utility can be used with squid to perform url redirection. It has a structured configuration system which allows greater control over url redirection. From Debian 3.0r0 APT

urlview

Extracts URLs from text This utility is used to extract URL from text files, especially from mail messages in order to launch some browser to view them. This used to be a part of mutt but has now become an independent tool. From Debian 3.0r0 APT

urpmi

urpmi takes care of dependencies between rpms, using a pool (or pools) of rpms. You can compare rpm vs. urpmi with insmod vs. modprobe From Mandrake 9.0 RPM

urw-fonts

Free, good quality versions of the 35 standard PostScript(TM) fonts, donated under the GPL by URW++ Design and Development GmbH. The fonts.dir file font names match the original Adobe names of the fonts (e.g., Times, Helvetica, etc.). Install the urw-fonts package if you need free versions of standard PostScript fonts. From Mandrake 9.0 RPM

usbmgr

User-Mode daemon which loads/unloads USB kernel modules When USB devices connect into or disconnect from a USB hub, the usbmgr works as the following according to configuration. a) Loads and unloads files Linux kernel modules. b) Execute file to setup USB devices. usbmgr is available under linux kernel have "/proc/bus/usb". From Debian 3.0r0 APT

usbutils

USB console utilities This applications show what the device tree of the USB bus looks like. It shows a graphical representation of the devices that are currently plugged in, showing the topology of the USB bus. It also displays information on each individual device on the bus. More information can be found at the Linux USB web site http://www.linux-usb.org/ . From Debian 3.0r0 APT

usbutils

usbutils contains a utility for inspecting devices connected to the USB bus. It requires a Linux kernel version 2.3.15 or newer (supporting the'/proc/bus/usb' interface). From Mandrake 9.0 RPM

usbview

USB device viewer USBView is a small GTK application to show what the device tree of the USB bus looks like. It shows a graphical representation of the devices that are currently plugged in, showing the topology of the USB bus. It also displays information on each individual device on the bus. More information can be found at the usbview web site http://www.kroah.com/linux-usb/ . From Debian 3.0r0 APT

user

n. 1. Someone doing `real work' with the computer, using it as a means rather than an end. Someone who pays to use a computer. See real user. 2. A programmer who will believe anything you tell him. One who asks silly questions. [GLS observes: This is slightly unfair. It is true that users ask questions (of necessity). Sometimes they are thoughtful or deep. Very often they are annoying or downright stupid, apparently because the user failed to think for two seconds or look in the documentation before bothering the maintainer.] See luser. 3. Someone who uses a program from the outside, however skillfully, without getting into the internals of the program. One who reports bugs instead of just going ahead and fixing them. The general theory behind this term is that there are two classes of people who work with a program: there are implementors (hackers) and lusers. The users are looked down on by hackers to some extent because they don't understand the full ramifications of the system in all its glory. (The few users who do are known as `real winners'.) The term is a relative one: a skilled hacker may be a user with respect to some program he himself does not hack. A LISP hacker might be one who maintains LISP or one who uses LISP (but with the skill of a hacker). A LISP user is one who uses LISP, whether skillfully or not. Thus there is some overlap between the two terms; the subtle distinctions must be resolved by context. From Jargon Dictionary

user interface

All the features of a program or computer that overs the way people Interact with the computer. See command driven program and graphical user interface (GUI) utility program A program that assists you in maintaining and Improving the efficiency of a computer system. Mtcrosoft Plus! includes the System Agent, a utility program that defragments your hard disk, compresses rarely used files, and corrects manor disk problems You can set the System Agent to work any time you leave your computer alone for a certain period of tame, or to run early in the morning every day. From QUECID

user-level (user-mode)

On an operating system, there are fundamental two contexts a program can run in. The kernel context is within the core of the operating system, and no checks are performed to see if accesses to system resources are legal. The other context is user-level, where full access to the system is walled-off. Key point: Many network services these days now run as restricted user-level processes. This means when a remote hacker breaks into such a service, they do not get full control over the machine. They might be able to deface a webpage or cause other havoc, but they do not own the box. At this point, the intruder will need to run some sort of privilege escalation exploit in order to root the system. From Hacking-Lexicon

user-mode-linux

User-mode Linux (kernel) User-mode Linux is a port of the Linux kernel to its own system call interface. It provides a kind of virtual machine, which runs Linux as a user process under another Linux kernel. This is useful for kernel development, sandboxes, jails, experimentation, and many other things. This package contains the kernel itself, as an executable program, and the associated kernel modules. From Debian 3.0r0 APT

useradd

Create a new user or update default new user information From whatis

userdel

Delete a user account and related files From whatis

userdrake

Userdrake is a user-friendly and powerful tool to add/edit/remove users from your Mandrake Linux system. From Mandrake 9.0 RPM

userinfo

display informations about a local user Userinfo is a small console utility to display as much information about a local user as possible. It currently supports: password file info, home directory mode, mail forwards/aliases/last read time/new time/folder size, utmp info and more... From Debian 3.0r0 APT

userland

n. Anywhere outside the kernel. "That code belongs in userland." This term has been in common use among Linux kernel hackers since at least 1997, and may have have originated in that community (a sighting has been reported from the 1995 archives of a NetBSD mailing list, however). From Jargon Dictionary

userlink-source

BSD IP Tunneling Driver for Linux (source package) This driver is based on BSD if_tun driver. If_tun driver exchanges IP packets between the character device and the network interface. From Debian 3.0r0 APT

usermod

Modify a user account From whatis

usermode

The usermode package contains several graphical tools for users:userinfo, usermount and userpasswd. Userinfo allows users to change their finger information. Usermount lets users mount, unmount, andformat filesystems. Userpasswd allows users to change their passwords. Install the usermode package if you would like to provide users with graphical tools for certain account management tasks. From Mandrake 9.0 RPM

usermode

The usermode package contains the userhelper program, which can be used to allow configured programs to be run with superuser privileges by ordinary users. From Redhat 8.0 RPM

username

a unique "name" by which each user is known to the system. This name is given to the user whenever they register to use the system. From Linux Guide @FirstLinux

users

print the user names of users currently logged in to the current host From whatis

userv

`user services' - program call across trust boundaries userv allows one program to invoke another when only limited trust exists between them. It is a tool which can be used to avoid having to give other system services root privilege, and which allows users to more securely have programs provide services to others. userv can be useful as `glue' for system administrators; there are not many full-blown userv-using applications yet. From Debian 3.0r0 APT

utah-glx

Hardware accelerated GLX module for XFree86 A hardware accelerated implementation of the GLX protocol for the XFree86 version 3 servers (this package only works with the XFree86 3.x X servers, the XFree86 4.x server comes with its own version of GLX). This package contains a loadable module for XFree86 that provides hardware accelerated OpenGL rendering for the following cards: * Matrox MGA-G200, MGA-G400 * NVidia Riva series * ATI Rage Pro (experimental) * Intel i810 * S3 ViRGE DX/GX/GX2/MX (experimental) * S3 Savage (experimental) From Debian 3.0r0 APT

utalk

talk-like program with additional features utalk uses a protocol, based on UDP, which ensures a quick response even over links with high packet loss, allows editing of previously typed text, including scrollback, deletion and overstrike, and provides some additional features. It is not compatible with BSD talk program. From Debian 3.0r0 APT

utempter

Utempter is a utility that allows some non-privileged programs to have required root access without compromising system security. Utempter accomplishes this task by acting as a buffer between root and the programs. From Redhat 8.0 RPM

util-linux

Miscellaneous system utilities. A mixed bag of system utilities: arch blockdev chkdupexe cfdisk cytune dmesg fdisk fsck.minix getty getopt hwclock ipcrm ipcs mcookie mkfs mkfs.minix mkswap more namei pivot_root raw rdev setterm setsid tunelp whereis. From Debian 3.0r0 APT

utility program

Program that supports using the computer. Utility programs, or "utilities," provide file management capabilities, text manipulation and archiving. Popular Linux utilities include grep, sed and kruiser. From Linux Guide @FirstLinux

utmp

allows one to discover information about who is currently using the system. There may be more users currently using the system, because not all programs use utmp logging. From Linux Guide @FirstLinux

uucp

Unix to Unix Copy Program UUCP will copy files to or from another (usually *nix) system, which also runs uucp. UUCP is used to transfer mail, news and random files between systems which are not connected by more modern networks. The communication can be made via modems, direct (hard-wired) serial connections or via an IP connection. From Debian 3.0r0 APT

uucp (Unix-to-Unix Copy)

UUCP is a service on a machine that can transfer files. In the olden days when connectivity was expensive, most machines were not connected together but where instead interconnected web of UUCP links. Machines would dialup peers and download/upload files on a scheduled basis. Most e-mail and USENET news were transported this way. E-mail addresses back in the 1980s consisted of long strings that specified each machine in the UUCP network. People held contests to see who could create the most convoluted route to send e-mail back to themselves over the long distance across the world. Key point: Even though it is rarely used today, uucp accounts and services are often enabled on UNIX machine in such a way that they can be exploited in order to break into the machine. See also: uuencode From Hacking-Lexicon

uucpsend

Alternatives Frontend for UUCP Batching This package provides some neat features to do UUCP batching. Partially it is logically based on send-uucp and nntpsend which were included in early versions of INN. From Debian 3.0r0 APT

uudecode

decode a file created by uuencode From whatis

uudeview

Smart multi-file multi-part decoder (command line) This is a command-line decoder and encoder for files encoded with the following formats: uuencode, xxencode, BASE64, quoted printable, and BinHex. This package used to contain an X11-based GUI decoder called xdeview. That program is now in the xdeview package. From Debian 3.0r0 APT

uuencode

encode a binary file From whatis

uuencode

format of an encoded uuencode file From whatis

uuidgen

command-line utility to create a new UUID value From whatis

uutraf

an UUCP traffic analyzer and cost estimator uutraf analyses your Log and Stats files and estimates the cost of your phone bill and UUCP provider bill. From Debian 3.0r0 APT

uw-imapd

remote mail folder access server IMAP (the Interactive Mail Access Protocol) is a mechanism for accessing mail folders and the messages in them remotely, ie with your user mail program running on a different machine to the one where all the messages are stored. If you do install uw-imapd you will almost certainly want to install a Mail Transfer Agent such as Smail or Sendmail, as remote mail programs which use IMAP to access incoming and saved mail will usually want to send mail using SMTP, often to the same machine. From Debian 3.0r0 APT

uw-imapd-ssl

remote mail folder access server IMAP (the Interactive Mail Access Protocol) is a mechanism for accessing mail folders and the messages in them remotely, ie with your user mail program running on a different machine to the one where all the messages are stored. If you do install uw-imapd you will almost certainly want to install a Mail Transfer Agent such as Smail or Sendmail, as remote mail programs which use IMAP to access incoming and saved mail will usually want to send mail using SMTP, often to the same machine. This server has SSL support built in. From Debian 3.0r0 APT

uwm

The ultimate window manager for UDE uwm is the ultimate window manager for UDE - the Unix Desktop Environment. UDE is more then just another windows manager. Designed to compensate for the shortcomings of many other similar packages, UDE features many innovative improvements. The project does not use any special GUI-Libraries such as Qt or GTK+ and is based on the standard Xlibs (also to make UDE faster) It features: * No title bars with icons etc. * High performance, since it just uses standard libraries UDE - get used to it... From Debian 3.0r0 APT

uxterm

terminal emulator for X, with Unicode support From whatis