Corso di Linux

 Ed eccoci arrivati alla sezione dedicata al Sistema Operativo Linux, l'unica vera alternativa a Windows ma che certo non può per diversi aspetti essere paragonato a quest'ultimo (per facilità d'uso ed immediatezza ad esempio).

+
E' un sistema molto potente
Richiede modeste risorse di sistema
Un semplice PC domestico può essere configurato come un SERVER
E' OPEN SOURCE

-
Non è assolutamente indicato ai meno esperti
Spesso necessaria una minima conoscenza di programmazione (concettuale)
Quantità di Dirver disponibili non paragonabile a quella di Windows

Comandi Linux

File Management


mkdir: Crea una directory
cd: Cambia la directory di lavoro
ls: Lista i file; simile al dir del dos
Cp: copia i file
mv: Sposta i file
rm: Rimuove un file o una directory
chmod: Cambia i permessi di un file (fondamentalmente Read, Write, Execute).
cmp: Compara due file
WC: Conta le parole, i caratteri e le righe di un file
compress: Comprime un file.


Comunicazioni

pine: Uno dei primi programmi di posta elettronica, facile da usare e abbastanza intuitivo.
talk: Serve per comunicare in tempo reale con un altro utente sulla stessa macchina, o su un host remoto. Funziona in tempo reale, con lo schermo diviso in due metà.
Write: Scrivere un messaggio che compare a video ad un altro utente. E abbastanza semplice: basta indicare il nome utente e, se si è in una grossa rete, anche il nome macchina : write root@enku.edu.
ftp: Programma per il trasferimento di file. Per abbandonare la sessione di file transfer digitate quit


Informazioni

man: Richiama il manuale in linea. l'utilizzo più elementare e': man nomecomando. Usando l'opzione -k è possibile visualizzare l'elenco dei comandi che contengono una parola chiave.
quota: Dà informazioni sullo spazio su disco a disposizione di un utente, nel caso fossero stati imposti dei limiti.
finger: Consente di cercare informazioni su un utente: fìnger root@enku.edu fornisce alcune informazioni sull'utente root, presente sulla macchina enku.edu.
passwd: Serve per cambiare la password di un utente; la sintassi è semplice, basta digitare il comando seguito dal nome. Attenzione, se non specificate alcun nome cambierete la password dell'utente che ha lanciato il comando.
who: Fornisce l'elenco degli utenti collegati al sistema.

Stampa

lpr: Stampa.
lprm: Rimuove un lavoro in coda di stampa.
lpstat: Informa sullo stato della coda di stampa.

Controllare il lavoro

ps: E' uno dei comandi più utilizzati dai sistemisti, dato che consente di avere una lista dei processi in esecuzione. Spesso viene utilizzato per visualizzare un processo in background o che sta rallentando il sistema.
kill: "Uccide un processo: dopo averlo individuato con ps, lanciate il comando kiII -9 PID (il PID è il numero che identifica un dato processo).
nohup: Questo comando risolve il problema di dover aspettare che un processo finisca per poter uscire dal sistema; nohup segiuito da un qualsiasi comando, fà in modo che quest'ultimo continui l'esecuzione anche dopo il logout
nice: Cambia la priorità di esecuzione di un processo
&: Come far lavorare un processo in background? Semplice: basta mettere una & finale.
Cntrl-z: Interrompe un processo in esecuzione.
fg: Riporta in foreground un processo mandato in background.

Salvare i Dati di lavoro e di sistema

cpio: Comando utilizzato per fare dei backup dei dati, si utilizza di solito per i salvataggi su nastro
tar: E' simile al comando cpio, ma crea degli archivi che possono essere facilmente scambiati su sistemi Unix differenti.
compress: E' uno dei primi compressori di file per Unix; viene ancora usato perché facile da usare e perché è tuttora considerato un comando standard; in alternativa si può utilizzare il più efficiente gzip.
uncompress: Decomprime i file compressi con compress.

Comandi di rete

netstat: Serve per controllare lo stato della rete, con il tag -r ci dà lo stato della tabella di routing.
ifconfig: Per sapere la configurazione di una scheda direte basta digitare il suo nome dopo il comando, ifconfig ethO fornisce la cor figurazione della scheda identificata dalla sigla ethO.
traceroute: Spesso per risolvere un problema di comunicazione tra pc bisogna conoscere dove si interrompe il flusso di dati; tracerout mostra quali host vengono attraversati dai pacchetti in viaggio ver un computer in rete.
route: Con le opzioni di add e delete permette di aggiungere o togliere una riga dalla tabella di routing.


Questa lista di comandi è stata gentilmente "offerta" dal pinguino Sad.

Software

di Antonio GALLO (che non sono io!)

Per Linux esiste una quantita' esagerata di Software distribuita in vari archivi all'interno della rete. Il software per Linux e' costituito al 99% da software sviluppato con licenza GPL/LGPL (o comunque rilasciato come OpenSource ).
Il software di base e' sviluppato e fornito dalla GNU Il software di sistema, comune ad altri sistemi operativi Unix, viene fornito tramite il mega archivio sunsite.unc.edu e dai suoi mirrors. Il software applicativo lo potete trovare sparso un po' ovunque in rete.
Dopo una breve panoramica dei vari tipi di software disponibili forniro' una serie di link a siti che vi permettono di accedere ad un catalogo di tutto il software disponibile e quindi scaricarlo sia in forma sorgente (de compilare) oppure gia' il pacchetto bello pronto per la vostra distribuzione.

Il software piu' usato in modalita' console

• Compilatori ^_^ : (tutti i compilatori per tutti i linguaggi)
• Lettori di posta: Mutt, Pine
• Lettori di news: slrn, tin, leafnode
• Browser internet: lynx
• Client FTP: ncftp

Il software piu' usato in modalita' grafica

Anche Linux ha la sua interfaccia grafica, chi l'avrebbe mai detto ! :-)
Si chiama X-Window (senza la "s" alla fine) ed e' il gestore del sistema di finestre. X-Window e' stato originariamente sviluppato al MIT, la versione per Linux e' stata scritta dall' XFree86 Project ed e' ovviamente rilasciata sotto licenza GPL/LGPL.
E' da notare che X-Window si incarica di gestire la sola parte interna di una finestra ...
... infatti per funzionare bene ha bisogno di un altro programmino che si chiama "Window Manager" che si prende carico di gestire l'iterazione tra l'uomo (mouse,tavoletta grafica,powerglove) e l'X-Window e non che di disegnare i bordi delle finestre.
I Window Manager piu' famosi sono: enlightenment, Windowmaker e Black Box
Ogni Window Manager gia' mette a disposizione una serie di menu' perl lanciare i programmi. Per avere un ambiente desktop completo ci sono varie alternativi: GNOME (che e' un progetto GNU), KDE oppure XFCE (che resembla il CDE del Solaris e del Digital).
Ed ecco invece i programmi piu' usati:

• Suite Office: Star Office, Applixware, Corel Word Perfect
• Browser internet: Netscape
• Grafica e Ritocco: GIMP (GNU Image Manipulation Program)

Dove prendere il software ?

Mandatemi una e-mail con oggetto: "Software Linux dove?" e una riga di saluto e vi darò ulteriori info...non è consentito inserire collegamenti ad altri server su questo sito...

Licenza GNU GPL
GNU GENERAL PUBLIC LICENSE - Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc. 675 Mass Ave, Cambridge, MA 02139, USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
Preamble
The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too. When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things. To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it. For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights. We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software. Also, for each author's protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations. Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all.
The precise terms and conditions for copying, distribution and modification follow.

GNU GENERAL PUBLIC LICENSE - TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The "Program", below, refers to any such program or work, and a "work based on the Program" means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term "modification".) Each licensee is addressed as "you".
Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does.
1. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program. You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee.
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a) You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change.
b) You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License.
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These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it. Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the Program.
In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License.
3. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following:
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This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License.
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NO WARRANTY
11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
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END OF TERMS AND CONDITIONS