Computers & Technology Unix

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Adviser to Unix BSD FreeBSD

 FreeBSDFrom Wikipedia, the chargeless encyclopediaFreeBSD is a Unix-like chargeless operating arrangement descended from AT&T UNIX via the Berkeley Software Administration (BSD) annex through the 386BSD and 4.4BSD operating systems. It runs on processors accordant with the Intel x86 family, as able-bodied as on the DEC Alpha, the UltraSPARC processors by Sun Microsystems, the Itanium (IA-64), AMD64 and PowerPC processors. It aswell runs on the PC-98 architecture. Abutment for the ARM and MIPS architectures is currently in development.FreeBSD is developed as a complete operating system. The kernel, accessory drivers and all of the userland utilities, such as the shell, are captivated in the aforementioned antecedent cipher afterlight tracking timberline (CVS). This is in adverse to Linux, a agnate but better-known operating system, in which the atom is developed by one set of developers; userland utilities and applications by others, such as the GNU project; and all are packaged calm by... Read More by user

Ad Hoc Data Assay From The Unix Command Band Background

 These book conventions will be acclimated if presenting archetype interactions at the command line:$ command argument1 argument2 argument3 achievement band 1 achievement band 2 achievement band 3 The $ is the carapace prompt. What you blazon is apparent in boldface; command achievement is in approved type.I will use the afterward sample files in the examples.The countersign book can be begin in /etc/passwd. Every user on the arrangement has one band (record) in the file. Anniversary almanac has six fields afar by colon (:) characters. The fields are username, encrypted password, userid, absence group, home agenda and absence shell. We can attending at the first few curve with the arch command, which prints just the first few curve of a file. Correspondingly, the appendage command prints just the endure few lines. $ arch -5 /etc/passwd root:x:0:0:root:/:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin lp:x:4:7:lp:/va... Read More by user

UNIX Accretion Aegis Advantageous accoutrement

 Appropriate topics: COPS, TIGER, sudo, md5, nfsbug, tripwire, OpenSSH, Linux Virtualization, SNORT, IDS/IPS, IPTables. ----There are a amount of bartering and chargeless software accoutrement accessible that are advised to advice the Arrangement Ambassador strengthen the aegis of their system. Depending on the aegis requirements, a amount of these utilities can be active on a approved base to strength-check their arrangement security, attending for break of an aggress or a compromised system, and apparatus added defended procedures.This admirable amalgamation consists of a alternation of scripts and binaries that can be acclimated to analysis some basal aegis configurations on a UNIX system. The endure amend to this amalgamation was adaptation 1.04, appear in 1991. appropriately this apparatus is starting to appearance its age, and may crave some accomplished affability to accomplish on a avant-garde adaptation of UNIX. The achievement will alter according to the UNIX bell-ringer and O... Read More by user

Adviser to UNIX Explanations Scheduling Jobs

 This describes how to use at and cron to agenda jobs in Linux. These commands behave similarily with additional Unix systems.Use at to agenda commands to run at specific times; use cron to agenda commands to run regularily and repeatedly. Examples:There are four methods to agenda jobs with at.You can aqueduct a command in from accepted input: $ answer ls / | at now + 1 minuteYou can let at apprehend your commands from accepted input: $ at 23:40 at> cd /tmp/perl5.005_56 at> make at> ls ?al at> ^DYou can use at -f to apprehend commands from a file: $ at ?f /root/bin/runme now + 5 hoursYou can use the accumulation command. You do not specify an beheading time; the job will run alone if the arrangement amount boilerplate is beneath a accurate value, by absence beneath 0.8: $ batch at> du ?h /home > /tmp/duhome at> ^DThere are two methods to appearance appointed jobs.You can use atq: # atq 5 2005-12-13 12:50 a root 6 2005-12-13 13:50 a root 7 2005-12-13 14:50 a root 8 2005-12-13 12:51 a swa... Read More by user

Adviser to Unix Explanations Free Accouterments

 Actuality are some methods of Free Accouterments currently on the system:Run dmesg on a $ dmesg | less ... OpenBSD 3.8 (GENERIC) #425: Sat Sep 10 15:49:26 MDT 2005 absolute mem = 268435456 (262144K) account mem = 236363776 (230824K) using 1254 buffers absolute 13418496 bytes of memory mainbus0 (root) ... mpcpcibr1 at mainbus0: uni-north, Afterlight 0x5 pci1 at mpcpcibr1 bus 0 ... macobio0 at pci1 dev 23 action 0 Angel Audacious rev 0x00 ... snapper0 at macobio0: irq 30,1,2 ... audio0 at snapper0 ...This arrangement has an OpenBSD 3.8 kernel, which matches the OpenBSD 3.8 operating arrangement distribution. (Generally, the atom on a The absolute anamnesis is 262144K, but alone 230824K is avail, which apparently agency available. Bisect by 1024 to catechumen to megabytes, using bc or some additional method: $ bc 262144 / 1024 256 230824 / 1024 225 quitThis computer has 256 MB of memory, but alone 225 MB are avail. Becaus... Read More by user

Adviser to Unix Explanations Addition to Editors

 The Addition to Editors briefly introduces the clairvoyant to the accepted Unix argument editors and provides links to added information.Many readers will be accustomed with argument editors that accept graphical user interfaces agnate to Block from Windows, TextEdit (in unstyled argument mode) from Mac OS X, GEdit from GNOME, or KEdit or KWrite from KDE. Additional readers will alone understand about chat processors, which are like argument editors, but accept added appearance for applying appearance and blueprint to the text. Argument editors alone accord with sequences of argument characters, all in the aforementioned font.The access of this affiliate is to acquaint the ancient Unix argument editors and advance to the Notepad-style editors. The aboriginal editors abridgement some accepted appearance of editors.One who uses the command line, but knows not how to use a argument editor, can still make argument files using the cat apparatus and the carapace redirection feature. $ cat > ... Read More by user
Tags: program, three, readers, people, press, keyboard, happens, common, screen, editor, features, editors, command, lines, document, chapter, commands

Adviser to Unix Explanations Best of Carapace

 All Unix shells are similar, but they accept altered features. If you are beginning, and you are not acquainted of the differences amid shells, then you apparently wish to alpha with a Bourne-compatible, POSIX-compatible carapace such as back-bite or ksh.These are the Bourne-compatible shells:BSD alien the C shell, which sometimes resembles hardly the C programming language. This carapace is csh. The carapace tcsh is csh with added features. These shells are NOT Bourne-compatible. Some of the appearance were after added to the Bourne-compatible shells (except old copies of sh). If these appearance plan abnormally in C carapace and Bourne-compatible shells, this adviser will call the Bourne-compatible shells.If csh or tcsh is your absence shell, you ability account by using back-bite or ksh to get Bourne-compatibility and POSIX features. Some users still adopt the C shell.There are another shells such as zsh, the Z shell. The Z carapace boasts added and abnormal appearance that create i... Read More by user

UNIX Accretion Aegis Data aegis

 Appropriate topics: backups to media, recovery, encryption and adversity recovery.Backup is actual capital in an ambiance area your data is precious, and that to a subset of data for about any computer user, if planning for a advancement system, there are some questions you charge to answer:if you are desinging your arrangement in a way to create it simple to backup, you could yield in application selecting a filing arrangement that supports usefull features, such as snapshots, XFS supports it, and ufs2 for (free?)bsd supports it.UNIX systems accommodate accoutrement that advice in abetment up, alotof frequently accepted is the tar command which allows creating athenaeum and buoy ownership/time-date/permessions on the files getting archived. those tar athenaeum can aswell calmly be compressed, using gzip for example.another apparatus to advancement is dump and restore, which depression absolute filing systems and treats it as a accumulating of deejay blocks, can be configured in /etc/f... Read More by user
Tags: system, backup, security, supports

UNIX Accretion Aegis Concrete aegis

 Appropriate topics: server room, media accumulator and arrangement connections.The concrete aegis of your accretion basement is at atomic as important as the measures that are activated at the software level. Crooked individuals accepting admission to a server allowance can ambush arrangement transmissions, couldcause servers to reboot from amid media, or accomplish awful abolition of your systems and data.Companies that amount their server accretion assets will about abode the systems in abandoned apartment with anxiously managed environments and protections adjoin ability outages. Admission to server apartment is bound by agency of locks that can crave aggregate codes, appropriate agenda cards, or biometric devices. The autogenous can be monitored using surveillance systems, such as ceiling-mounted camera domes. Ambit aegis is provided by architecture admission mechanisms and aegis personnel.However not all the accretion basement can be adequate to this degree. Admission to the arran... Read More by user

UNIX Accretion Aegis Log files and auditing

 Appropriate topics: syslog, lpds log, mail log, install, Audit, and IDS.----Log files are generated by arrangement processes to almanac activities for consecutive analysis. They can be advantageous accoutrement for troubleshooting arrangement problems and aswell to analysis for inappropriate activity. The UNIX releases are preconfigured to almanac assertive advice in log files, but agreement settings are accessible to access the bulk of advice recorded.Log files can be actual advantageous assets for aegis adventure investigations. They can aswell be capital for case of bent activity. For these causes log files should be periodically backed up to separate media, and precautions charge to be taken to anticipate analytical with the log files. It is expeced that an crooked burglar into a accretion arrangement will attack to abolish any trace of their activities from the arrangement log files.For log files that tend to abound decidedly in admeasurement over the advance of time, it can be ac... Read More by user
Tags: activity, usually, files, information, activities, system, administrator, media, security, events, capability, messages

UNIX Accretion Aegis Limited admission

 Appropriate topics: modems, ftp, rlogin, ssh, UUCP, NFS, Samba, and Apache.----This command is acclimated to authorize a affiliation with addition host that can be accessed via the network, and acquaint with it using the TELNET protocol. About telnet is acclimated to affix to a user login via the accepted TELNET port. For the absence configuration, the login countersign is beatific beyond the arrangement in clear-text form. That is to say, if the arrangement packets amid the two hosts are getting apprehend by some intermediary, then the countersign cord will arise in the packets in a clear form. Additionally any data beatific through during the affair will aswell arise in clear form, including any additional defended advice beatific to the limited hosts.Normally, if you wish to advance the aegis of your communications, the absence agreement of telnet should alone be active on arrangement segments that you are awful assured are secure. Establishing such a arrangement is acceptable more ... Read More by user

UNIX Accretion Aegis Accepting accounts

 Appropriate topics: carapace environment, countersign aging, countersign strength, dot files, belted shells, abeyant accounts, defended terminals and basis access.----The users of a Unix arrangement are alotof acceptable not about as abreast about the aegis aspects of their arrangement as are the Arrangement Administrators. So it is important to use the agreement capabilities of the arrangement to configure these accounts so that they are analytic secure. Such agreement can be activated to the absence user aegis settings, the environments in which programs will be run, and so forth. There may aswell be appropriate restrictions bare for assertive accounts depending on admission and data aegis requirements on the server.Once an annual is in use, the Arrangement Ambassador will still charge to apply a assertive akin of vigilence to create assertive the admission is not abused, or even coopted by an inappropriate person. Passwords charge to be arrested for backbone and periodically updated... Read More by user

UNIX Accretion Aegis UNIX filesystem

 Appropriate topics: aggregate managers, book systems, files, directories, ls, find, chown, chgrp, chmod, umask, setuid, setgid, accessory files, ACLs.----Most of the data acclimated by a computer is stored on Deejay storage. These are concrete accessories with a about top admission latency, compared to, say, concrete memory, but ample accumulator capacity. On a server arrangement a deejay drive can be amid central the aforementioned chiffonier as the Axial processing unit, an adjoining amplification cabinet, absorbed to the arrangement as an Network-attached storage, or absorbed as allotment of a Accumulator breadth network. Some sites may aswell apply removeable deejay media that can be loaded by an abettor or a automatic device.The Book arrangement is the adjustment by which data on a device, such as a deejay drive, is laid out. It includes advice that the operating arrangement can use to acquisition specific data agreeable and who is accustomed to admission that data. All of this da... Read More by user

UNIX Accretion Aegis Admission approval

 In adjustment to affix to a UNIX-based arrangement and accomplish activities, a user haveto accept an account. This annual haveto accept a different after identifier, which is associated with the annual name, or username. The annual aswell has a password, which is cord accepted to the user by which the annual admission is accurate if accessing the system. The username and countersign are commonly acceptable to affix a user to the system.Users can accept assorted accounts on the aforementioned system, or accounts on altered systems. Anniversary annual can use a altered name, if they are on the aforementioned system, or allotment a accepted name beyond assorted systems. Depending on the being or academy operating the systems, the alone users may be able to accept their annual names, or they may be assigned a name. About an assigned name will be based on the bodies absolute name, and will be a different identifier on the system.The username is aswell the login name, which agency that it i... Read More by user
Tags: account, access, program, usually, based, problems, change, systems, accounts, files, users, information, activities, individuals, system, different, example, individual, administrator, difficult

UNIX Accretion Aegis Attempt and behavior

 Appropriate topics: education, accident administration and enforcement, government aegis levels (C2, &c.)----Computing aegis as it applies to UNIX is usually taken to beggarly aegis of a UNIX-based accretion arrangement adjoin crooked admission to advice or casework on that system, including viewing, copying, modifying or antibacterial data.But aegis can aswell administer to crooked attempts to abjure adapted individuals admission to the stored advice through accident of availability. Aegis is aswell acclimated to administer aloofness on a system, whether by acknowledging the character of a being who performed an action, and by acceptance individuals to advance ascendancy of clandestine information.Providing aegis to a arrangement is not a ambition so abundant as it is an advancing process. At atomic at present, a UNIX accretion arrangement can never be create absolutely secure. About by always applying a alternation of aegis measures to the systems, the net accident to the arrangement... Read More by user

UNIX Accretion Aegis Addition

 UNIX is a computer operating arrangement that was first developed during the 1960s and 1970s at AT&T Alarm Labs. It was originally conceived as an bookish operating system, decidedly at the university level, and appropriately aegis was not a top antecedence of the design. Back then, however, UNIX accretion systems accept been create added broadly accessible and accept become an capital allotment of networking and internet infrastructure. The added akin of admission and the charge for data aegis accept apprenticed improvements to UNIX aegis features. The change of UNIX aegis appearance continues to this day, with an more burning charge for preventing inappropriate admission to systems and their data.This book is advised for an admirers that has at atomic a basal acquaintance with the UNIX operating system, including accepted carapace commands, the agenda structure, and book manipulation. The primary focus will be for the Arrangement Ambassador of a UNIX system. That is the abettor who i... Read More by user
Tags: access, systems, system, operating, security, features

Adviser to Unix Explanations bc

 bc is an arbitrary-precision calculator language. The arbitrary-precision agency that numbers can accommodate absolute digits (limited by memory); alotof additional languages absolute numbers to eight bytes at most. For addition, subtraction, and multiplication, there is absolute precision. Analysis stops afterwards a assertive amount of decimal places (usually 0 or 20), so bc is generally bad with actual baby numbers (like 10e-44).bc is generally alleged using the -l option, which endless the accepted library (which mostly contains accurate functions) and sets the amount of decimal places for analysis to 20. (Doing accurate with the absence attention of 0 decimal places is not so useful.)This is an archetype of a user starting bc, accomplishing two calculations, and exitting with quit. Agenda that acute ^D (control-D) aswell exits. $ bc -l 3 + 4 7 2 / 5 .40000000000000000000 quit $This Software accouterments Simpsons aphorism for integration. The action accommodate approximates the de... Read More by user

Adviser to Unix Ambiance Variables

 An ambiance capricious is a ambience commonly affiliated or declared if a carapace is started. You can use shells to set variables; the syntax varies but Absolute shells use: $ VARNAME=new value $ consign VARNAME or $ consign VARNAME=new valueEach program started from that carapace will accept VARNAME set to new value. The names of ambiance variables are case-sensitive; by assemblage they are uppercase.A carapace capricious is like an ambiance variable, except that it is not exported to new programs started from that shell. (You could consign it, but commonly you just address a carapace initialisation Software to set it in anniversary shell.) The editor program alleged by sudoedit, vipw, and additional such programs if you acquaint them to adapt a file.Examples: EDITOR=vi EDITOR=emacsThe home agenda of the user. Alotof programs use this carapace capricious to acquisition your home, appropriately you can set this capricious to override the ambience in /etc/passwd for your home directory... Read More by user
Tags: absolute, program, programs, email, systems, example, started, boxes, value, examples, profile, directory, environment, scripts, editor, searches, refers, command, setting, string

Adviser to Unix Why Unix-like

 The operating arrangement installed on some server and some computer workstation is Unix-like. But what does it beggarly to be Unix? In this book, a Unix-like arrangement is one that is agnate to . The closing actuality allows alotof Unix-like systems to run the aforementioned and .The carapace is a program different to Unix-like systems. It lets you blazon commands to barrage additional programs.When you login to the arrangement through a text-only terminal, Unix gives you a login shell. If your arrangement has a graphical user interface such as , , or annihilation that uses , you can admission the carapace through a program alleged a animate adversary or terminal emulator. This emulates the text-only terminal that the carapace requires for running.Unfortunately, the carapace and the commands are harder to learn. Further, some commands crave arguments to work. For example, the rm command, which removes files, needs one or added arguments allotment the files to delete. This book has a ... Read More by user

Adviser to Unix Explanations Ambiance

 Every program inherits ambiance variables from the program that started it. This agency that anniversary program has the aforementioned ambiance variables as the program that started it. The ambiance of a program can change, in which case additional programs after started by that program aswell accept a afflicted environment.The ambiance capricious alleged Carapace contains the name of the absence shell. (You ability be active some additional shell, but the absence carapace is consistently in SHELL.) The Carapace ambiance capricious is set during login and affiliated by the shell. If we started the printenv program, it affiliated the absolute environment, including SHELL, and showed Carapace to us.Using printenv with no arguments gives the absolute environment: $ printenv ... SHELL=/bin/bash ...See to apprentice about specific variables.Each action has banned on the following.Limits are affiliated from the ancestor process. The accustomed way to set banned is to change the banned of so... Read More by user



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