Chapter 2 - File and Directory Management - Operating Systems 2 - PDF

Operating Systems 2 TECM 113  Chapter 2: File and directory management Dr/ Amina Magdich TECM 113 2  Chapter 2: File and directory management Chapter outline  I. Introduction  II....

Operating Systems 2 TECM 113  Chapter 2: File and directory management Dr/ Amina Magdich TECM 113 2  Chapter 2: File and directory management Chapter outline  I. Introduction  II. Linux Directory structure  III. Directories and Files management  IV. Removable Storage  V. Conclusion Dr/ Amina Magdich TECM 113 3  Chapter 2: File and directory management I. Introduction:  The objectives of this chapter are:  Understand and navigate the linux directory structure using relative and absolute pathnames  Use standard linux commands to manage files and directories  Describe the various types of linux files  Display the contents of text files and binary files  Search text files for regular expressions using grep  Use the vi editor to manipulate text files Dr/ Amina Magdich TECM 113 4  Chapter 2: File and directory management II. Linux Directory structure:  Directory: used to organize other files into a logical tree structure  Absolute pathname: pathname from the root directory (/) to a certain file or directory  Root: the top level directory - Referred to using the / character - Forms root of a hierarchical tree Dr/ Amina Magdich TECM 113 5  Chapter 2: File and directory management II. Linux Directory structure: Figure 2.1: the windows file system Dr/ Amina Magdich structure TECM 113 6  Figure 2.2: The Linux file system Dr/ Amina Magdich structure TECM 113 7  Table 2.1: Linux directories defined Dr/ Amina Magdich TECM 113 8  Chapter 2: File and directory management II. Linux Directory structure:  Changing directories:  Home directory: unique to each user  pwd (print working directory) command: displays current directory in the directory tree  cd (change directory) command: change the current directory in the directory tree Argument specifies the destination directory  ~metacharacter: refers to home directory (personal directory) Dr/ Amina Magdich TECM 113 9  Chapter 2: File and directory management II. Linux Directory structure:  Changing directories:  Relative pathname: pathname of file or directory relative to current directory  Parent directory: directory one step closer to the root of the tree $cd..  Subdirectory: directory residing within another directory  Tab-completion: pressing the tab key fills in remaining characters Dr/ Amina Magdich of a unique file name or directory name TECM 113 10  Chapter 2: File and directory management III. Directories and File management:  Viewing files and directories: file types  Text files: store information in a readable text format, contain configuration information  Binary data files: store information associated with executable programs  Executable program files  Directory files: serve as place holders to organize other files Dr/ Amina Magdich TECM 113 11  Chapter 2: File and directory management III. Directories and File management:  Viewing files and directories: file typesfiles: associated with another file  Linked  Special device files: represent system devices  Named pipes: identify channel that passes information between processes  Socket files: Allow a process on another computer to write to a local file Dr/ Amina Magdich TECM 113 12  Chapter 2: File and directory management III. Directories and File management:  File names  File name: identifier given to a file  File name extensions: identifiers following a dot (.) at end of file name  Most files on Linux do not have file extensions Dr/ Amina Magdich TECM 113 13  Chapter 2: File and directory management Table 2.2: Common file name Dr/ Amina Magdich extensions TECM 113 14  Chapter 2: File and directory management Table 2.3: Common file name Dr/ Amina Magdich extensions TECM 113 15  Chapter 2: File and directory management III. Directories and File management:  Directory management  mkdir command: creates new directories  Use –p to create more than one directory Example: $mkdir /home/Lina/MyFolder $mkdir -p /home/Lina/Folder1/Folder2/Folder3 Dr/ Amina Magdich TECM 113 16  Chapter 2: File and directory management III. Directories and File management:  Directory management  mv command: to move files  Two arguments minimum: - Source file/directory - Target file/directory $mv source Destination mv is also used to rename files Example: $mv /home/Lina/File1 /home/Lina/File2  to rename file1 to Dr/ Amina Magdich File2 TECM 113 17  Chapter 2: File and directory management III. Directories and File management:  Directory management  Exercice: Move the directory Dir 1 from /home/Asmaa to /home (/home/Asmaa/Dir1) $mv /home/Asmaa/Dir1 /home Dr/ Amina Magdich TECM 113 18  Chapter 2: File and directory III. Directories and File management: management  Directory management  cp command: to copy files  Two arguments minimum: - Source file/directory - Target file/directory $cp source file target file Use –r to copy the folder and its content (when the folder is not empty) Example: $cp -r /home/Lina/Folder1 /home/Lina/MyFolder  to copy Dr/ Amina Magdich TECM 113 19  Chapter 2: File and directory management III. Directories and File management:  Directory management  rm command: to remove files or directories  rmdir command: remove empty directories  -r is used to remove a directory and its content Example: $rmdir /home/Lina/MyFolder (MyFolder is empty) to delete an empty directory $rm -r /home/Lina/MyFolder (MyFolder is not empty) to delete a directory and its content $rm Dr/ Amina/home/Lina/File1 Magdich to delete a file TECM 113 20  Chapter 2: File and directory management III. Directories and File management:  Directory management Table 2.4: Common Linux file management Dr/ Amina Magdich TECM 113 21  Chapter 2: File and directory management III. Directories and File management:  File management  Listing files  ls command: List the files in a directory - May pass an argument indicating the directory to be listed -F: argument to list file types -l: argument to list long file listings (listing with details) https://www.youtube.com/watch?v=3MfaZFUC1yE Dr/ Amina Magdich TECM 113 22  Chapter 2: File and directory management III. Directories and File management:  File management  Listing files  file: the file command displays the file type of any file  Example: $file TECM113.txt Ascii text: means text file Figure 2.3: Examples of the file command use Dr/ Amina Magdich TECM 113 23  Chapter 2: File and directory management III. Directories and File management:  File management  Listing files  Hidden files: Files not normally displayed to users  File names start with a dot (.)  Configration files are often hidden  $ls –a : displays all the files including hidden files  Example:  $ls -a /home Dr/ Amina Magdich TECM 113 24  Chapter 2: File and directory management III. Directories and File management:  File management  Listing files Option Description -a Lists all the files (with hidden files) -A Lists all the files excluding the. And.. Special files -C Lists files in column format -f Lists all the files without sorting -F Lists the files classified by type adds an « / » after the name of each directory, an « * » after a file and an « @ » after a link -r Lists files reverse sorted Table2.5: Common options to the ls Dr/ Amina Magdich command TECM 113 25  Chapter 2: File and directory management III. Directories and File management:  File management  Listing files Option Description -R Lists the files in the specified directory and all subdirectories -s lists the files and their associate size in kilobytes (KB) -S Lists the files sorted by the file size -t Lists the files sorted by modification time Table2.6: Common options to the ls command https://www.youtube.com/watch?v=2QQk4LJvJP4 https://www.youtube.com/watch?v=2zVvIrhF5KA https://www.youtube.com/watch?v=2zVvIrhF5KA Dr/ Amina Magdich TECM 113 26  Chapter 2: File and directory management III. Directories and File management:  File management  Listing files  Alias: shortcut for a command  Example: $alias C= " clear " https://www.youtube.com/watch?v=vIt4aYcVpQE https://www.youtube.com/watch?v=uLYxq_B8s44 $alias: allows to list the existent alias Dr/ Amina Magdich TECM 113 27  Chapter 2: File and directory management III. Directories and File management:  File management  Creating files touch command: to create an empty file Example: $touch /home/Lina/OS  allows to create a file named OS Dr/ Amina Magdich TECM 113 28  Chapter 2: File and directory management III. Directories and File management:  File management  Displaying content of text files less file more file cat file Example 1: $cat /etc/passwd  to display the content of the file passwd Example 2: $less /etc/passwd  to display the content of the file passwd Dr/ Amina Magdich TECM 113 29  Chapter 2: File and directory ABC TECM management III. Directories and File management: DEF OS  File management 1. ABC  Displaying content of text files 2. DEF  Concatenation: joining text together 3. TECM 4. OS  cat command : displays (concatenates) contents of a text file to the screen -n: displays line number and contents Example 1: $cat /etc/passwd  to display the content of the file passwd Example 2: $cat test Dr/ Amina test 1  concatenates the content of the files Magdich TECMtest 113and 30  Chapter 2: File and directory management III. Directories and File management:  File management  Displaying content of text files head file: to view the first ten (10) lines of a file Example :  The command  The Result Dr/ Amina Magdich TECM 113 31  Chapter 2: File and directory management III. Directories and File management:  File management  Displaying content of text files To limit the number of lines using head use the –n option followed by the number of lines to show Example :  The command  The Result Dr/ Amina Magdich TECM 113 32  Chapter 2: File and directory management III. Directories and File management:  File management  Displaying content of text files $tail file: to view the last 10 lines of a file Example : Dr/ Amina Magdich TECM 113 33  Chapter 2: File and directory management III. Directories and File management:  File management  Displaying content of text files It is possible to specify the number of lines to display using the option -n Example : Dr/ Amina Magdich TECM 113 34  Chapter 2: File and directory management A III. Directories and File management: B C  File management D  Displaying content of text files  tac : displays files in reverse order $cat file1 $tac file1 Example: A D $ tac File B C C B D A Dr/ Amina Magdich TECM 113 35  Chapter 2: File and directory management III. Directories and File management:  File management  grep command  grep is the acronym of Global Regular Expression Print  grep is used to search for a string of characters in a specified file.  It displays lines in a text file matching a given string  grep requires two arguments : text to search for and files to search Syntax: $grep stringToMatch File Dr/ Amina Magdich TECM 113 36  Chapter 2: File and directory management III. Directories and File management:  File management  grep command Example: Dr/ Amina Magdich TECM 113 37  Chapter 2: File and directory management III. Directories and File management:  File management  Editing text files  vi  One of the oldest and most popular text editor for UNIX OS:  vi : Linux editor which works the same across different platforms and distributions  Syntax:  vi filename_new or vi filename_Existing  Example:  $vi text1 https://www.youtube.com/watch?v=o08un9UEuWo Dr/ Amina Magdich TECM 113 38  Chapter 2: File and directory management III. Directories and File management:  File management  Editing text files:  To write in the file press i  shift+zz to save and close the file  :w to save the file but keep it open  :q! to quit without saving  :wq to save the file and quit https://www.youtube.com/watch?v=o08un9UEuWo Dr/ Amina Magdich TECM 113 39  Chapter 2: File and directory management III. Directories and File management:  File management Dr/ Amina Magdich TECM 113 40  Chapter 2: File and directory management III. Directories and File management:  File management Dr/ Amina Magdich TECM 113 41  Chapter 2: File and directory management III. Directories and File management:  File management Dr/ Amina Magdich TECM 113 42  Chapter 2: File and directory management III. Directories and File management:  File management Dr/ Amina Magdich TECM 113 43  Chapter 2: File and directory management III. Directories and File management:  File management  Editing text files (vi command): Table2.7: Common keyboards keys used to change to and Dr/ Amina Magdich TECM 113 from insert mode 44  Chapter 2: File and directory management Table2.8: Key combinations commonly used at the Dr/ Amina Magdich command mode: prompt TECM 113 45  Chapter 2: File and directory management III. Directories and File management:  File management  Editing text files  vim  vim: Linux equivalent of vi (it is vi improved)  Syntax:  vim  Example:  $vim text1 https://www.youtube.com/watch?v=CM7UP-un1vc Dr/ Amina Magdich TECM 113 46  Chapter 2: File and directory management III. Directories and File management:  File management  Editing text files  mcedit editor (Midnight Commander Editor) - Easy ti use - Supports use of mouse for highlighting text Syntax: $mcedit Example: $mcedit Text1 https://www.youtube.com/watch?v=QuyakInZjvg Dr/ Amina Magdich TECM 113 47  Chapter 2: File and directory management III. Directories and File management:  File management  Editing text files  emacs editor (Editor MACroS) - Comparable functionality to vi - Supports LISP (LISt Processing) artificial intelligence programming language Syntax: $emacs Example: $emacs Text1 https://www.youtube.com/watch?v=4jQmS0gS-lU Dr/ Amina Magdich TECM 113 48  Chapter 2: File and directory management III. Directories and File management:  File management  emacs editor (Editor MACroS) Table2.9: keyboard functions commonly used in the GNU Dr/ Amina Magdich emacs editor TECM 113 49  Chapter 2: File and directory management III. Directories and File management:  File management  Editing text files  emacs editor (Editor MACroS) - emacs is not easy to use: must memorize key combinations - xemacs editor: version of emacs for KDE or GNOME GUI environments Easier to use than emacs Not available with every distribution Dr/ Amina Magdich TECM 113 50  Chapter 2: File and directory management III. Directories and File management:  Editing text files  xemacs editor The xemacs text Dr/ Amina Magdich editor TECM 113 51  Chapter 2: File and directory management III. Directories and File management:  File management  Editing text files  nedit editor  gedit editor: distibuted with GNOME environment  kedit editor: distributed with KDE environment  gedit and kedit offer more functionality than nedit Dr/ Amina Magdich TECM 113 52  Chapter 2: File and directory management III. Directories and File management: The nedit text Dr/ Amina Magdich editor TECM 113 53  Chapter 2: File and directory management III. Directories and File management: The gedit text Dr/ Amina Magdich editor TECM 113 54  Chapter 2: File and directory management III. Directories and File management: The kedit text Dr/ Amina Magdich editor TECM 113 55  Chapter 2: File and directory management III. Directories and File management:  File management  Log files  Log files: contain records of past system events Dr/ Amina Magdich TECM 113 56  Chapter 2: File and directory management IV. Removable storage:  File systems  A file system is a way of organizing files on your partition.  The linux kernel will inform you about currently loaded file system drivers in /proc/filesystems  /proc/filesystems file contains a list of autodetected filesystems Dr/ Amina Magdich TECM 113 57  Chapter 2: File and directory management IV. Removable storage:  Common file systems  Ext2 and ext3  The most common linux file systems is the ext2. A disadvantage is that file system checks on ext2 can take a long time  Ext2 was replaced by ext3  Ext2 and Ext3 are the same, except for the journaling wich is only present in ext3. Dr/ Amina Magdich TECM 113 58  Chapter 2: File and directory management IV. Removable storage:  Common file systems  Ext4  It is a new file system which is available in the linux kernel since 2008.  It supports larger files than ext3  Xfs  Is a file system supported in Redhat.  It is a highly scalable high-performance file system Dr/ Amina Magdich TECM 113 59  Chapter 2: File and directory management IV. Removable storage:  Common file systems  Vfat  The vfat file system exists in a couple form: fat12 for floppy disks, fat 16 on msdos, and fat32 for larger disks.  Fat disks can be read by every OS.  Iso 9660  Is the standard format for cdrooms  Udf, swap, gfs, reiserfs, and so on … Dr/ Amina Magdich TECM 113 60  Chapter 2: File and directory management IV. Removable storage:  Mounting volumes  The mount command mounts a storage device or filesystem, making it accessible and attaching it to an existing directory structure  Once you put a file system on a partition (or insert a cd), you can mount it.  Mounting a file system makes it available for use, usually as a directory.  Syntax: mount Dr/ Amina -t type-device directory Magdich TECM 113 61  Chapter 2: File and directory management IV. Removable storage:  Mounting volumes  Example:  To access files on a cd-rom, you must mount the cd-rom on a location in the directory tree mount -t /dev/cdrom /media/cdrom $mount –t /dev/cdrom /MyCD  /dev/cdrom is the type of the device  /media/cdrom is the chosen mount point (a directory that exists or that Dr/ Amina must be created before applying the command) Magdich TECM 113 62  Chapter 2: File and directory management IV. Removable storage:  Unmounting volumes  The unmount command unmounts a mounted filesystem, informing the system to complete any pending read or write operations and safely detaching it  Example: unmount /media/cdrom Dr/ Amina Magdich TECM 113 63  Chapter 2: File and directory management IV. Conclusion ▸ The Linux file system is arranged hierarchically using a series of directories to store files ▸ Location of these directories and files can be described using absolute or relative pathnames ▸ Text files are the most common file type whose contents can be viewed by several utilities such as head, tail, cat, more and less Dr/ Amina Magdich TECM 113 64