Dal 23/04/09 è disponibile la versione RC di Ubuntu Jaunty Jackalope (Lepre Cornuta disinvolta). Il download può essere effettuato da qui però indiscrezioni dicono che via torrent ci sia già la versione finale.

Vediamo le novità di questo nuovo file system: * Supporto ai volumi grandi, ora fino a 1024 Pib (1 pebibyte = 1015 byte), insomma molto più spazio per i porno :-D . * Extent: gli extent vengono utilizzati per mappare un gruppo di blocchi contigui con un singolo descrittore, un extent può mappare fino a 128MB con una dimensione del blocco pari a 4KB. * Compatibilità in avanti con ext3, quindi se abbiamo creato una partizione con ext4 possiamo montarla tranquillamente come ext3. Però se la partizione ext4 creata usa gli extent si perde la compatibilità in avanti. * Compatibilità all'indietro, un filesystem ext3 può essere montato come ext4 usando ext4dev come tipo di filesystem. * Preallocazione persistente: il filesystem ext4 permette senza problemi di allocare in anticipo spazio disco per un file. * Allocazione ritardata: in ext4 l'allocazione dello spazio disco è ritardata fino al flush, invece di avvenire in seguito alla chiamata write. Quindi ridotta frammentazione del disco e i file temporanei non vengono scritti sul disco (ma solo in memoria) vista la loro breve permanenza. In questo modo si risparmiano cicli di scrittura e cancellazione. * Rimozione del limite di 32000 sottodirectory di ext3. * Ext4 avrà un tool che permette di deframmentare singoli file o l'intero file system. * Controllo dell'integrità con e2fsck molto più rapido. * Timestamp in nanosecondi. Quindi con la prossimo release del Kernel, la 2.6.28 per essere precisi, il nuovo file system sarà rilasciato in versione stabile.

Using the GCC compiler Automating builds with make The preceding post, “Programming Environments and Interfaces,” provided a high-level view of Linux programming, focusing on the overall development environment and introducing the idioms that give programming on a Linux system its distinctive character. This chapter goes into greater detail and describes some of the tools and toys found on a typical Linux development system. Examining library utilities Exploring source code control The goal of this chapter is not to turn you into a developer in 30 pages or less, but simply to explore some of the variety of tools developers use so you will at least know what they are and what they do. You’ll also learn how to use some of the programs and utilities. Debugging with GDB

If you are using Linux over a network or from a dumb terminal (a monitor that allows only text input with no GUI support), your shell may be all that you have. You may be used to a windowing environment where you have a lot of programs active at the same time so that you can switch among them as needed. This shell thing can seem pretty limited. Although the bash shell doesn’t include a GUI for running many programs, it does let you move active programs between the background and foreground. In this way, you can have a lot of stuff running, while selectively choosing the one you want to deal with at the moment. There are several ways to place an active program in the background. One mentioned earlier is to add an ampersand (&) to the end of a command line. Another way is to use the at command to run commands in a way in which they are not connected to the shell.

Linux File Systems Versus Windows-Based File Systems Although similar in many ways, the Linux file system has some striking differences from file systems used in MS-DOS and Windows operating systems. There are a few: In MS-DOS and Windows file systems, drive letters represent different storage devices (for example, A: is a floppy drive and C: is a hard disk). In Linux, all storage devices are fit into the file system hierarchy. So, the fact that all of /usr may be on a separate hard disk or that /mnt/rem1 is a file system from another computer is invisible to the user.

Command-Line Recall After you type a command line, that entire command line is saved in your shell’s history list. The list is stored in a history file, from which any command can be recalled to run again. After it is recalled, you can modify the command line, as described earlier. To view your histor y list, use the history command. Type the command without options or followed by a number to list that many of the most recent commands

Although similar in many ways, the Linux file system has some striking differences from file systems used in MS-DOS and Windows operating systems. Here are a few: In MS-DOS and Windows file systems, drive letters represent different storage devices (for example, A: is a floppy drive and C: is a hard disk). In Linux, all storage devices are fit into the file system hierarchy. So, the fact that all of /usr may be on a separate hard disk or that /mnt/rem1 is a file system from another computer is invisible to the user.

Bash Configuration Files File Description /etc/profile Sets up user environment information for every user. It is executed when you first log in. This file provides values for your path, as well as setting environment variables for such things as the location of your mailbox and the size of your history files. Finally, /etc/profile gathers shell settings from configuration files in the /etc/profile.d directory. /etc/bashrc Executes for every user who runs the bash shell, each time a bash shell is opened. It sets the default prompt and may add one or more aliases. Values in this file can be overridden by information in each user’s ~/.bashrc file.

If you have a dual-boot Windows/Linux system, you probably know this problem: you can access files from your Windows installation while you are in Linux, but not the other way round. This tutorial shows three ways how you can access your Linux partitions (with ext2 or ext3 filesystem) from within Windows: Explore2fs, DiskInternals Linux Reader, and the Ext2 Installable File System For Windows. While the first two provide read-only access, the Ext2 Installable File System For Windows can be used for read and write operations.

Gli hard disk, le singole partizioni e altri dispositivi di memorizzazione come lettori CD e DVD possono essere montati e smontati, cioè resi accessibili, anche all'avvio, tenendo conto delle impostazioni presenti nel file di configurazione /etc/fstab. È qui, infatti, che si stabilisce l'associazione tra dispositivo (ad esempio /dev/hda1, /dev/hdb2, /dev/hdc1, ecc.) e punto di mount all'interno del file system, cioè la directory dove il contenuto di un hard disk o di una partizione diventerà disponibile. Inoltre, sempre attraverso /etc/fstab è possibile stabilisce il tipo di file system utilizzato per la formattazione del supporto (Ext3, ReiserFS, Xfs, ISO9660...) e i permessi di accesso: possibilità di montare e smontare il disco, anche in automatico, accesso in lettura e scrittura e molte altre opzioni.