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Chapter 8. Disks and Filesystems

Chapter 8. Disks and Filesystems. Ordinary Files. What is a file? a container for ordered data persistent (stays around) and accessible by name Unix files regular Unix files are pretty simple essentially a sequence of bytes Unix files are identified by a name in a directory

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Chapter 8. Disks and Filesystems

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  1. Chapter 8. Disks and Filesystems

  2. Ordinary Files • What is a file? • a container for ordered data • persistent (stays around) and accessible by name • Unix files • regular Unix files are pretty simple • essentially a sequence of bytes • Unix files are identified by a name in a directory • this name is actually used to resolve the hard disk name/number, the cylinder number, the track number, the sector, the block number • you see none of this • it allows the file to be accessed

  3. Files, Directories, Devices • Unix files come in other flavors as well, such as • Directories • a file containing pointers to other files • equivalent of a “folder” on a Mac or Windows • Links • a pointer to another file • used like the file it points to • similar to “shortcuts” in Windows, but better • Devices • access a device (like a soundcard, or mouse, or ...) like it is a file

  4. Figure 3-3 A Directory Hierarchy

  5. System Directories • Some standard directories and files in a typical Unix system • / the root • /bin BINaries (executables) used to start system • /sbin System BINaries for Superuser • /lib LIBraries used for startup • /dev DEVices (peripherals) hardware interfaces • /etc unique settings for system, config, passwds • /usr Biggest filesystem, sys tools, X, apps • /tmp temp storage, good to separate partition

  6. Typical System Directory Contents • /usr USeR stuff • /usr/bin BINaries again • /usr/include include files for compilers • /usr/lib LIBraries of functions etc. • /usr/local local stuff for apps installed later • /usr/local/bin local BINaries • /usr/local/lib local LIBraries for apps • /usr/X11R6 X window stuff • /usr/sbin sysadmin stuff • /usr/tmp place for more TeMPorary files • /var VARiable stuff—mail, print jobs, logfiles • /var/mail the mail spool • /var/log security info VERY IMPORTANT

  7. The /proc filesystem • /proc is a virtual directory. in RAM rather than in HDD. • /proc contains info about your system’s state. amount of free memory processes running external devices plugged in remaing battery power if you are working in a laptop • You can, though, navigate around it with cd command and list its contents with ls command or view some of its file contents with cat command

  8. The /proc file system • Numbers are directories representing each of the running process on the system and contain all info related to it. terra$ ls /proc/480/ auxv cwd exe maps mounts stat status wchan cmdline environ fd mem root statm task For example: cmdlinecontains the command the process started with memcontains the amount of memory this process holds • . /proc contains information about the hardware of the system cat /proc/meminfo contains information about memory state more /proc/ioports gives all the information about the availability of I/O ports on the system and the hardware device assigned to each.

  9. Figure 3-8 Inodes Each file on the disk has an inode which keeps information about the file, it’s address, etc

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