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Chapter 6

Chapter 6. Linux File System. File System. File System management how to store informations on storage devices The Hierarchical Structure Types of file Common File system Tasks. /. home. etc. bin. boot. usr. dev. lib. root. …. local. bin.

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Chapter 6

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  1. Chapter 6 Linux File System

  2. File System File System management how to store informations on storage devices • The Hierarchical Structure • Types of file • Common File system Tasks

  3. / home etc bin boot usr dev lib root … local bin The Hierarchical Structure of the Linux File System

  4. The Hierarchical Structure of the Linux File System • / - first of mount point in linux • /bin - contains shells (bash) and file system management utilities • /etc - keep linux text-based configuration files • /boot - keep important linux booting files • /dev - keep all device files • /usr - keep all user binary and X library • /home - keep user home directory • /proc - is pseudo file system for tracking running process and state of linux system

  5. The Hierarchical Structure of the Linux File System • /var - keeping variable data, log file and printer spooling • /lib - contain shared library that is required by system program • /tmp - contain system temporary file • /root - the root user’s home directory • /sbin - contains important system management and admin files (fdisk, fsck, ifconfig, init, mkfs, shutdown, halt) • /media - system use to mount externel devices (CD/DVD , floppy drives) (or /mnt)

  6. The Hierarchical Structure of the Linux File System • Files in /etc directory

  7. The Hierarchical Structure of the Linux File System • FHS (Filesystem Hierarchy Standard) provide a standard directory structure for the file system, ensuring consistency between systems and distributions. • http://www.pathname.com/fhs

  8. Types of Files • Regular files • Links • FIFOs • Sockets

  9. Navigating the File System • Path • absolute path • Current directory& relative path • Home directory (~) • pwd, cd, ls • pwd (Present Working Directory) • Display the current directory $ pwd • cd • Change the current directory $ cd /var/log $ cd.. $ cd ~ (or press cd )

  10. Navigating the File System • pwd, cd, ls • ls • List the files and subdirectories that exist within a directory $ ls / $ ls /bin $ ls –l / $ ls –a /var/run $ ls –R /var/run $ ls

  11. Navigating the File System $ ls –l ~ 1 file type 2 Owner’s /Group/Other Permissions 3 Number of link 7 Last Update datetime 6 Size 5 Group’s name 4 Owner’s name 8 File/Dir name

  12. Navigating the File System • File type • normal file - • Block device file b • Character device file c • Directory d • Link file l • Permissions on file /directory • Read r • Write w • Execute x

  13. Creating Files and Directories • Creating a new file : touch or vi • touch command touch myfile.txt // size = 0 • Using a Text editor vi newfile.txt vi /home/user1/file.txt • Creating a directory : mkdir mkdir myDir mkdir /home/ti/myDir mkdir -p /home/ti/aa/bb

  14. Viewing text file content • cat, more, less, head, tail cat filename |more more filename less filename • Auto stop when full screen. Using spacebar, page up, page down, arrow keys when viewing head filename • Display the first couple of lines of a text file tail filename • Display the last couple of lines of a text file • tail –f filename : display new content to be added to the end of the file

  15. Copying, moving, deleting • cp, mv, rm, rmdir cp /tmp/schedule.txt ~ //copy file cp –R ~/myDir ~/backup //copy dir. mv /tmp/mylog.txt /var/log //move file mv myfile.txt mynewfile.txt //rename rm filename //delete file rm -r dirname //delete directory rm -i filename //prompt rmdir dirname//delete empty directory

  16. Using wildcard charaters • * , ? , [ab] , [a-z] Example : there are these files in current directory vd.txt, vda.txt, vdb.txt, vdabc.txt, vd1.txt, vd22.txt , vd3.txt $ cp *.txt /home/an //copy 7 files $ cp vd[1-5].txt /home/an // copy 2 file $ cp vd[ab].txt /home/an // copy 2 file

  17. Link files • Hard link and Symbolic link (soft link) • Pointers a different file/directory in the file system • Symbolic link : similar shortcut in Windows OS • ln pointee_file pointer_file • ln -s pointee_file pointer_file (pointee_file = source file/dir pointer_file = hard link/ symbolic link file) $ ln -s /usr/share/doc/ ~/docs

  18. Running executable file Linux OS searches through the directories listed in your PATH environment variable for the executable file you specified. • Adding a new path to the $PATH PATH=$PATH:newpath • Determine resident of exec file which $ which vi /usr/bin/vi $ which ls /bin/ls

  19. Searching the File System • find , locate, grep • Find utility searchs for files of a specified name, or owner, or size • Using *, ? when specified name find path -name “filename” find path -user “username” find path -size “size” find path -size “+size” find path -size “-size” find / -name “*.log” find / -user “root” find / -size “+100”

  20. Searching the File System • Locate utility builds an index of the files. When searching files, locate runs a query of the index, doesn’t search the file system directly. • Locate runs much faster than find • To use locate , must first install the findutils-locate package

  21. Searching the File System • Using grep to search for content within a file grep search_text file grep –r “help” /*.txt grep “help” *.txt

  22. Manage Disk Partitions • Using fdisk to create disk partitions • Building a file system with mkfs • Mounting a partition with mount • Checking the file system with fsck

  23. Storage Devices In Linux system , storage devices is referenced as device files that stored in /dev directory.

  24. M B R 1 2 3 4 primary M B R 1 2 3 4 5 6 7 8 logical extended Partitions • Primary and Extended partitions • On the IDE hard disk, up to four primary partitions • One of the primary partitions can be extended partition • Include many logical partitions

  25. Partitions • Each Partition is referenced as one device, and have a device file in /dev • Partitions as sda1, sda2, sda3 ,… have corresponding device driver files as /dev/sda1, /dev/sda2, /dev/sda3, … • Ex. fdisk /dev/sda mount /dev/sda2

  26. File system • A file system style is the way that data is organized to store in the storage device • Linux supports many of fs styles • ext2, ext3, ext4, reiser ,… // Linux • vfat, fat32, ntfs // Windows • iso9660,… //cdrom • File system term also refer to a partition has been formatted with a file system

  27. Hình: Hệ thống tập tin ảo File system • Linux uses a Virtual File System (VFS) that creates a single hierarchy that encompasses all partitions on all storage devices in the system

  28. sda / sda1 sda2 home etc bin usr sda3 local bin sda4 Logic file system Storage device Mount • Mount the partition into an existing directory in your file system, before can use it (read/write data).

  29. sda / sda1 sda2 home etc bin usr sda3 hda1 local bin sda4 logic file system Storage device Unmount • Unmount the partition into a directory Storage device

  30. Unmount • T1 : / được mount với sda1 $ ls /usr/local vd1.txt • T2: /usr được mount với sda2 $ vi /usr/local/vd2.txt $ ls /usr/local ??? • T3: umount /usr với sda2 $ ls /usr/local ???

  31. Using fdisk to create disk partitions • Syntax : $ fdisk /dev/sdb =>press m to open menu • Choose p to view partition table • Choose n to make new partition • Choose d to delete a partition • Choose w to write table and exit, or q to exit without saving

  32. Using fdisk to create disk partitions • To make a new partition • Choose making a primary partition or extended partition ? • Size of partition (MB or start and end cylinder) • Have to create at least two partitions on a primary hard disk : swap partition and root partition • a swap partition • OS uses it as virtual memory • it’s size is at least twice as large as your installed RAM

  33. Using fdisk to create disk partitions

  34. Using fdisk to create disk partitions • To view the partition table $ fdisk -l

  35. Building a file system with mkfs • mkfs • Used to make an ext2 or ext3 (or FAT) file system on a partiton mkfs -t ext3 /dev/sda2 • mkreiserfs • Used to make a Reiser file system on a partition mkreiserfs /dev/sdc3 • Other utilities : • mkswap, mk2fs, mkfs.msdos, mkfs.vfat

  36. Mounting a partition with mount • mount command syntax: mount –t type devicetarget-dir • type : ext2, ext3, reiserfs, … • device : /dev/hda1, /dev/hdb1, … • target-dir : /, /var, /home, /mnt/cdrom, …

  37. / hda3, ext2 /var /home hda4,ext2 hda1,ext2 Mounting a partition with mount • Using mount command $ mount –t ext2 /dev/hda3 / $ mount –t ext2 /dev/hda4 /home $ mount –t ext2 /dev/hda1 /var

  38. Mounting a partition with mount • After mounting the partition, you can use the mount command with no options to view all mounted file systems. Or using df utility $ mount $ df (the mount command uses mtab file to view all mounted file systems )

  39. Mounting a partition with mount • Automatically mount when the system boot or reboot • The /etc/fstab file contains a list of file systems that the operating system mounts whenever it boots. • Each line specifies a separate file system to be mounted on boot partition mount_point fs_type options dump check

  40. Mounting a partition with mount • You can add a new mount partition entry in /etc/fstab that Linux will automatically mount at boot. - Using vi editor to open /etc/fstab, then add the new line …

  41. unmount • Using umount command: two ways umount dir_name umount device_name • Have to unmount before unplug removable devices • Unmount to free the mount point • Automatically unmount when the OS shutdowns (halt)

  42. Đĩa USB : /dev/sdb • Có 2 partittion /dev/sdb1 /mnt/usb1 /dev/sdb2 /mnt/usb2 • Cần rút đĩa USB => thực hiện unmount umount /dev/sdb umount /dev/sdb1 umount /dev/sdb2 Hoặc: umount /mnt/usb1 umount /mnt/usb2

  43. Checking the file system with fsck • Using fsck to check your file systems for errors and make repairs fsck device $ fsck /dev/sdc1

  44. Use Removable Media • Floppies, optical devices, USB, FireWire devices • Need to mount with a directory • Need to unmount before remove

  45. Working with floppy $ mount –t vfat /dev/fd0 /media/floppy $ mount $ vi /etc/fstab /dev/fd0 /media/floppy auto noauto,user,sync 0 0 $ mount /dev/fd0 $ umount /dev/fd0

  46. Working with optical devices • mount –t iso9660 /dev/hdc /media/cdrom • Adding a line in /etc/fstab file : /dev/hdc /media/cdrom iso9660 noauto,user,sync 0 0 so, mount a cdrom by entering mount /dev/hdc • umount /dev/hdc

  47. USB , FireWire devices • Automatically detect a new device when connect an external storage device • SCSI device • Check /var/log/messages file after connecting the device • Create on the device • A partition • A file system • Mount device mount –t auto /dev/sdd /media/thumbdrive • umount the device before remove it

  48. Using YaST • YaST utility • Install software, manage hardware settings, partition hard drives, configure bootloaders, configure network board, configure users and groups, settings for the services running on system • Ex. : Using YaST to partition on usb disk

  49. Back up data • Selecting a Backup Medium • Floppies, tape drive • CDs, DVDs • USB • External hard drives

  50. Back up data • Selecting a Backup Strategy • Selecting Backup type : Full Incremental Differential • Selecting a backup schedule • Determining what to back up

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