2. Xarakthristika toy Linux

• Multitasking: polla programmata trexoyn taytoxrona.
• Polyxrhstiko (multiuser): polloi xrhstes sto idio mhxanhma taytoxrona (kai kamia anagkh gia polles adeies xrhsth!).
• Metafersimo (multiplatform): trexei se polles diaforetikes CPUs, oxi mono stoys epejergastes ths Intel.
• Multiprocessor: Yparxei hdh yposthrijh SMP stis Intel kai SPARC platformes (me thn doyleia na exei jekinhsei kai se alles platformes), kai to Linux xrhsimopoieitai se polles MP efarmoges, symperilambanomenwn kai twn systhmatwn Beowulf (deite to <http://cesdis.gsfc.nasa.gov/linux-web/beowulf/beowulf.html>) kai ston Fujitsu AP1000+ yperypologisth poy basizetai sthn SPARC arxitektonikh.
• Trexei se prostateymenh katastash (protected mode) ston 386 kai toys newteroys Intel epejergastes.
• Exei prostasia mnhmhs metaju twn diergasiwn, etsi wste ena programma na mhn mporei na ``katebasei'' olo to susthma.
• Fortwnei otan yparxei anagkh ta ektelesima: to Linux diabazei apo to disko mono ekeina ta merh enos programmatos poy pragmatika xrhsimopoiountai.
• Koines copy-on-write selides metaju twn ektelesimwn. Ayto shmainei oti polles diergasies mporoun na xrhsimopoioun tis idies perioxes mnhmhs gia na trexoyn. Otan kapoia prospa8hsei na gracei sthn mnhmh, ekeinh h selida (ena kommati 4KB ths mnhmhs) antigrafetai kapoy allou. To copy-on-write exei duo pleonekthmata: ayjanei thn taxuthta kai meiwnei thn mnhmh poy apaiteitai.
• Ideath mnhmh xrhsimopoiwntas selidopoihsh (den kanei swapping oloklhres diergasies) kai meros toy diskoy: se ena jexwristo partition h ena arxeio sto susthma arxeiwn, h kai ta duo, me thn dynatothta gia pros8hkh perissoterwn swapping perioxwn se runtime xrono (nai, akoma legontai swapping perioxes). Synolika to polu 16 swapping perioxes twn 128 MB mporoun na xrhsimopoiountai taytoxrona, dinontas ena 8ewrhtiko orio twn 2 GB sthn synolikh swapping perioxh. Einai aplo, omws, na allajei to orio ayto, tropopoiwntas liges grammes kwdika.
• Mia enopoihmenh phgh mnhmhs gia programmata xrhsth kai cache diskwn, etsi wste olh h eleu8erh mnhmh na mporei na xrhsimopoih8ei gia caching, kai h cache na mporei na meiw8ei otan trexoyn megala programmata.
• Dynamika fortwsimes diamoirasmenes biblio8hkes (dynamically linked shared libraries) (alliws gnwstes kai ws DLL's). Bebaia, yposthrizei kai statikes biblio8hkes.
• Dhmioyrgei core dumps gia ek twn ysterwn analysh, dinontas thn dynatothta gia xrhsh enos debugger se ena programma oxi mono otan trexei, alla ki afou exei crash-arei.
• Symbato se ena megalo pososto me to POSIX, to System V, kai to BSD se epipedo phgaioy kwdika.
• Mesw enos iBCS2-symbatou tmhmatos ejomoiwshs, symbato me SCO, SVR3, kai SVR4 se dyadiko (ektelesimo) epipedo.
• Olos o phgaios kwdikas einai dia8esimos, symperilambanomenoy oloklhroy toy kernel kai olwn twn odhgwn, twn ergaleiwn anaptyjhs kai olwn twn programmatwn xrhsth! Epishs, oloklhro to Linux mporei na dianemetai eleu8era oloklhro. Polla emporika programmata yparxoyn dia8esima gia Linux xwris ton phgaio kwdika, alla oti htan eleu8era dia8esimo, symperilambanomenoy oloklhroy toy basikou leitoyrgikou systhmatos, einai akomh eleu8era dia8esimo.
• Elegxos ergasiwn symbatos me POSIX.
• pseudoterminals (pty's).
• Ejomoiwsh ths 387 FPU mesa sto idio to kernel etsi wste ta programmata den xreiazetai na kanoyn thn dikh toys ejomoiwsh. Ka8e ypologisths poy trexei to Linux moiazei na exei ena ma8hmatiko synepejergasth. Bebaia, an o ypologisths sas exei hdh mia FPU, 8a xrhsimopoih8ei ayth anti gia thn ejomoiwsh, kai mporeite na xtisete ton pyrhna sas xwris ayth thn ejomoiwsh, gia na kerdisete ligh mnhmh.
• Yposthrijh gia polla e8nika kai prosarmosima plhktrologia -- einai arketa eukolo na proste8oun kainouria dynamika otan yparjei anagkh.
• Pollaples ideates konsoles: arketa anejarthta login sessions apo thn konsola toy systhmatos, allazete patwntas ena syndyasmo apo hot-keys (anejarthta apo to video hardware). These are dynamically allocated; you can use up to 64.
• Yposthrizei polla koina systhmata arxeiwn, symperilambanomenwn twn minix, Xenix, ola ta koina system V filesystems (p.x. UFS), kai exei ena diko toy ejeligmeno susthma arxeiwn, to opoio prosferei systhmata arxeiwn mexri 4 TB, kai onomata poy periexoyn mexri 255 xarakthres. Epipleon, sto susthma arxeiwn toy Linux, o monos periorismos poy yparxei sto poioys xarakthres mporei na periexei ena onoma einai oti den mporei na periexei ton xarakthra ASCII NUL (0) (anti8eta me to VFAT, p.x. poy apagoreuei toys xarakthres ``*?<>|":/\\+=,; []'').
• Diafanh prospelash twn arxeiwn enos MS-DOS partition (h OS/2 FAT partition) mesw enos eidikou systhmatos arxeiwn: den xreiazeste eidikes entoles gia na xrhsimopoihsete to MS-DOS partition, moiazei san ena kanoniko Unix susthma arxeiwn (ektos apo merikous asteioys periorismous sta onomata twn arxeiwn, thn prostasia twn arxeiwn, ktl.). Ta sympiesmena partitions toy MS-DOS 6 den doyleuoyn ayto ton kairo xwris ena patch (dmsdosfs). To Linux 2.0 yposthrizei to VFAT (WNT, Windows 95).
• Eidiko susthma arxeiwn, poy legetai UMSDOS, to opoio yposthrizei thn egkatastash toy Linux se ena DOS partition.
• Yposthrijh (gia anagnwsh-mono) toy HPFS-2 (OS/2 2.1).
• Yposthrijh gia to HFS (Macintosh) file system yparxei jexwrista san module.
• CD-ROM filesystem which reads all standard formats of CD-ROMs.
• TCP/IP networking, including ftp, telnet, NFS, etc.
• Appletalk ejyphrethths
• Netware pelaths kai ejyphrethths
• Lan Manager (SMB) pelaths kai ejyphrethths
• Polla diktyaka prwtokolla: ta basika prwtokolla poy einai dia8esima sta teleytaia peiramatika kernels perilambanoyn ta TCP, IPv4, IPv6, AX.25, X.25, IPX, DDP (Appletalk), NetBEUI, Netrom, kai alla. Sta8era diktyaka prwtokolla poy periexontai sta sta8era kernels perilambanoyn ta TCP, IPv4, IPX, DDP, and AX.25.