File System Discovery           -
Question ?What do you know      about  File System ?
What is file system ?> Method of storing and organizing computer filesand their data.> Essentially, it organizes these fil...
What is file system hierarchy ?To put it simply, it can be visualized as    a tree with its roots and all.At the top of th...
Different from WindowsWindows starts with drives, which areexplicit– C:– D:
Root !!In Windows, every drive has its own root C:is the root of the C driveIn Linux, there is only one root, no matterhow...
AttentionWindows uses a backslash for everythingLinux uses a forward slash for everythingIn Windows, the logical drive (e....
Drives vs. directoriesIn Windows, drives are directoriesIn Linux, you can have several drivesall under one overall directory
Standard?Distros can vary, but so can programsWhen you install a program, it may not followthe FHS in deciding where to pl...
/This is the symbol for the root of the filesystem in LinuxEvery directory is “under” root, ultimatelyThis is not the same...
Let’s Zoooooooooooom
/binContains many of the commands used on thecommand lineExamples include cat, chmod,dmesg, kill, ls,mkdir more, ps, pwd, ...
/bootContains files needed for boot – kernel – Grub menu (good to know if you aredualbooting) – Lilo boot sector backupsCo...
/devKinda-sorta an equivalent to a mashup of theDevice Manager and C:WindowsSystem inWindowsContains a file describing eve...
/dev 2hda1, hda2, etc. are partitions on the firstphysical IDE drivesda1, sda2, etc. are partitions on the firstphysical S...
/etcPerhaps the most important to understandNo binaries can be here, per the standardThis is just for configuration filesE...
/etc 2These files are generally text files and can beedited using any text editor:emacs or vi onthe command line, or whate...
/etc/inittabDescribes what takes place at bootup Includesthe runlevel of the system, and whichprocesses should be run at e...
/etc/fstabAutomatically mounts file systems acrossmultiple drives or partitions, or even fromremote systemsThis file tells...
/etc/fstabAutomatically mounts file systems acrossmultiple drives or partitions, or even fromremote systemsThis file tells...
/etc/hostsThis is the famous hosts file, which matchesup names with IP addressesThis is like level 1 DNS. The system looks...
/etc/passwdThis is the password file, but it contains more:user name, user password, user ID, group ID,home directory, and...
/etc/opt/This is a directory for the configuration filesfor each system application you install.Each application gets its ...
/etc/x11Configuration directory for x11, which is thedisplay system for graphical interfaces inLinuxThis can vary with dif...
/homeThis is where the home directories for all ofthe “ordinary” users are located.The exception is root, which has its ow...
/home Partition?Your home directory is where youwould place all of your documents, videos,MP3s, etc.It can get fairly larg...
ReinstallingIf you have a separate /home partition, youcan reinstall (or do a clean upgrade) and stillkeep not only your d...
/libThis is the location for shared library files thatare used by system programsShared library files are equivalent to Wi...
/lib 2Also in this directory are kernel modulesOther library locations for other programsinclude /usr/lib and /usr/local/lib
/media, /mntEither directory can be a place to mountremovable media (e.g. CD, USB drive, Floppydisk)/mnt is the older way,...
/optIntended as a place for “optional” software,i.e. add-on packages that are not part of thedefault installation
/procHave we mentioned that everything in Linux isa file or a directory?Any time a process is created in Linux, acorrespon...
/rootHome directory for the root accountNormally, you dont want to be root, and youdont want to go here
/sbinPlace for System binariesOne of three such directories– /sbin– /usr/sbin– /usr/local/sbinAll three hold utilities use...
/tmpGuess what this one is?Yes, temporary files are placed hereAssume that anything in this directory will bedeleted whene...
/usrLots of stuff in hereBack in the mists of prehistory, these werethe user directories, equivalent to what arenow /home ...
/usr/binContains executable files for many LinuxcommandsThese are commands that are not part of thecore Linux operating sy...
/usr/includeGeneral use include files, including headerfiles, for C and C++ programming languages
/usr/libContains libraries for the C and C++programming languagesObject files, libraries, and internal files notintended t...
/usr/localFor use by System Administrator wheninstalling software locallyMust not be over-written when systemsoftware is u...
/usr/sbinNon-essential standard system binaries, i.e.utilitiesEssential utilities go in /sbin
/usr/share/manPrimary location for man pages for the system
/usr/srcSource code is placed here, for referencepurposes onlyThis includes the source code for the Linuxkernel
/varThis is for files that are expected to beupdated and changedThis includes:– mail directories– print spool– logs– web s...
/var 2Because these can be written to constantly,they can grow over timeOn a server, you may want to put /var on itsown pa...
/var/lockContains lock filesThese files prevent two users (or twoprograms) from trying to access the samedata at the same ...
/var/logContains the log files generated by programs
The end ☺
File system discovery
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File system discovery

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File system discovery

  1. 1. File System Discovery -
  2. 2. Question ?What do you know about File System ?
  3. 3. What is file system ?> Method of storing and organizing computer filesand their data.> Essentially, it organizes these files into adatabase for the storage, organization,manipulation, and retrieval by the computersoperating system. Eg:- fat, ntfs, ext4, ext3.......
  4. 4. What is file system hierarchy ?To put it simply, it can be visualized as a tree with its roots and all.At the top of the hierarchy is invariably the root path which is represented by / and all other directories are created beneaththis root path in linux.
  5. 5. Different from WindowsWindows starts with drives, which areexplicit– C:– D:
  6. 6. Root !!In Windows, every drive has its own root C:is the root of the C driveIn Linux, there is only one root, no matterhow many drives you may have– In Linux, / is the rootRoot is ambiguous in one respect, since it canrefer to the top of the file structure, and isalso the name of the Administrator typeaccount in Linux.
  7. 7. AttentionWindows uses a backslash for everythingLinux uses a forward slash for everythingIn Windows, the logical drive (e.g. C:) is animportant part of the directory structureIn Linux, logical drives dont mean much. You caneven mount a separatephysical drive under a directory that is on anotherdrive.In Windows, case does not matterIn Linux, everything is case sensitive.
  8. 8. Drives vs. directoriesIn Windows, drives are directoriesIn Linux, you can have several drivesall under one overall directory
  9. 9. Standard?Distros can vary, but so can programsWhen you install a program, it may not followthe FHS in deciding where to place its files
  10. 10. /This is the symbol for the root of the filesystem in LinuxEvery directory is “under” root, ultimatelyThis is not the same as the user “root”, whichis the user with God-like powers over thesystemThe user “root” does have a directory, called /root
  11. 11. Let’s Zoooooooooooom
  12. 12. /binContains many of the commands used on thecommand lineExamples include cat, chmod,dmesg, kill, ls,mkdir more, ps, pwd, sed, suthe above commands, and many others,must be in /bin to meet the standard.Other commands can be optionally included,such as tar. gzip, netstat, and ping
  13. 13. /bootContains files needed for boot – kernel – Grub menu (good to know if you aredualbooting) – Lilo boot sector backupsContains data that is used before the kernelstarts executing user-mode programs
  14. 14. /devKinda-sorta an equivalent to a mashup of theDevice Manager and C:WindowsSystem inWindowsContains a file describing every device, andthese files can send data to each deviceIn Linux, everything is a file or a directory
  15. 15. /dev 2hda1, hda2, etc. are partitions on the firstphysical IDE drivesda1, sda2, etc. are partitions on the firstphysical SATA drive/dev/cdrom is the optical drive/dev/fd0 is the floppy drive, if you have one/dev/dsp is the speaker device
  16. 16. /etcPerhaps the most important to understandNo binaries can be here, per the standardThis is just for configuration filesExamples include /etc/inittab, /etc/fstab ,/etc/passwd , /etc/hosts, /etc/x11, and /etc/opt
  17. 17. /etc 2These files are generally text files and can beedited using any text editor:emacs or vi onthe command line, or whatever graphicalequivalent (e.g. gedit, kate) your desktopoffers
  18. 18. /etc/inittabDescribes what takes place at bootup Includesthe runlevel of the system, and whichprocesses should be run at each runlevelLinux has seven runlevels, from 0-6
  19. 19. /etc/fstabAutomatically mounts file systems acrossmultiple drives or partitions, or even fromremote systemsThis file tells the system what drive to access,and where to mount it in your system
  20. 20. /etc/fstabAutomatically mounts file systems acrossmultiple drives or partitions, or even fromremote systemsThis file tells the system what drive to access,and where to mount it in your system
  21. 21. /etc/hostsThis is the famous hosts file, which matchesup names with IP addressesThis is like level 1 DNS. The system looks herefirst.This can be used to block sites by puttingtheir URL in here
  22. 22. /etc/passwdThis is the password file, but it contains more:user name, user password, user ID, group ID,home directory, and shell.It can optionally contain the users “realname”Each user is on its own lineEach user can select the shell they want touse (most use bash these days)
  23. 23. /etc/opt/This is a directory for the configuration filesfor each system application you install.Each application gets its own subdirectoryunder /etc/opt/
  24. 24. /etc/x11Configuration directory for x11, which is thedisplay system for graphical interfaces inLinuxThis can vary with different distros, so againyou need to check/etc/x11/xorg.conf is the configuration filethat lets you specify the resolutions yourmonitor and graphics card can display, forinstance
  25. 25. /homeThis is where the home directories for all ofthe “ordinary” users are located.The exception is root, which has its own homedirectory, /root/Each user gets a directory with their username: e.g. /home/devmixThis can contain configuration files forapplications that are user-specific
  26. 26. /home Partition?Your home directory is where youwould place all of your documents, videos,MP3s, etc.It can get fairly largeIt is also the stuff you want to back up, andyou dont want to losePutting it on its own partition, or even its ownphysical drive, is not a bad idea
  27. 27. ReinstallingIf you have a separate /home partition, youcan reinstall (or do a clean upgrade) and stillkeep not only your data, but many of your fileconfigurations
  28. 28. /libThis is the location for shared library files thatare used by system programsShared library files are equivalent to Windows“*.dll” filesThe files here are intended to be libraries forprograms in /bin and /sbin, i.e. needed toboot the system and run the commands in theroot file system
  29. 29. /lib 2Also in this directory are kernel modulesOther library locations for other programsinclude /usr/lib and /usr/local/lib
  30. 30. /media, /mntEither directory can be a place to mountremovable media (e.g. CD, USB drive, Floppydisk)/mnt is the older way, and is still used fortemporarily-mounted file systemsMost current distro versions will mount thesedevices automatically
  31. 31. /optIntended as a place for “optional” software,i.e. add-on packages that are not part of thedefault installation
  32. 32. /procHave we mentioned that everything in Linux isa file or a directory?Any time a process is created in Linux, acorresponding file goes in hereGosh, what would happen if you deleted a filehere?
  33. 33. /rootHome directory for the root accountNormally, you dont want to be root, and youdont want to go here
  34. 34. /sbinPlace for System binariesOne of three such directories– /sbin– /usr/sbin– /usr/local/sbinAll three hold utilities used for systemadministration, and are intended for the rootuser like for booting, restoring, recovering,and/or repairing the system
  35. 35. /tmpGuess what this one is?Yes, temporary files are placed hereAssume that anything in this directory will bedeleted whenever the system is bootedIf you want to have your own temporarydirectory and not lose files at reboot, createone in your home directory, i.e./home/username/temp
  36. 36. /usrLots of stuff in hereBack in the mists of prehistory, these werethe user directories, equivalent to what arenow /home directoriesNow /usr is for shareable dataNot intended for software packages, ingeneral
  37. 37. /usr/binContains executable files for many LinuxcommandsThese are commands that are not part of thecore Linux operating systemThey would go in /binExamples of commands in here: perl, python
  38. 38. /usr/includeGeneral use include files, including headerfiles, for C and C++ programming languages
  39. 39. /usr/libContains libraries for the C and C++programming languagesObject files, libraries, and internal files notintended to be executed directly by users orshell scripts
  40. 40. /usr/localFor use by System Administrator wheninstalling software locallyMust not be over-written when systemsoftware is updatedGenerally has same subdirectories as /usr
  41. 41. /usr/sbinNon-essential standard system binaries, i.e.utilitiesEssential utilities go in /sbin
  42. 42. /usr/share/manPrimary location for man pages for the system
  43. 43. /usr/srcSource code is placed here, for referencepurposes onlyThis includes the source code for the Linuxkernel
  44. 44. /varThis is for files that are expected to beupdated and changedThis includes:– mail directories– print spool– logs– web sites
  45. 45. /var 2Because these can be written to constantly,they can grow over timeOn a server, you may want to put /var on itsown partition to limit the growthThis can also prevent the /var directory frombringing down the server by using up all ofthe drive space.
  46. 46. /var/lockContains lock filesThese files prevent two users (or twoprograms) from trying to access the samedata at the same timeYou may need to delete a lock file from timeto time
  47. 47. /var/logContains the log files generated by programs
  48. 48. The end ☺

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