Unix Tutorial

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CHAPTER 25 Unix – File System Basics Afile system is a logical collection of files on a partition or disk. A partition is a container for information and can span an entire hard drive if desired. Your hard drive can have various partitions which usually contains only one file system, such as one file system housing the / file system or another containing the /home file system. One file system per partition allows for the logical maintenance and management of differing file systems. Everything in Unix is considered to be a file, including physical devices such as DVD-ROMs, USB devices, floppy drives, and so forth. Directory Structure: Unix uses a hierarchical file system structure, much like an upside-down tree, with root (/) at the base of the file system and all other directories spreading from there. A UNIX filesystem is a collection of files and directories that has the following properties: It has a root directory (/) that contains other files and directories. Each file or directory is uniquely identified by its name, the directory in which it resides, and a unique identifier, typically called an inode. By convention, the root directory has an inode number of 2 and the lost+found directory has an inode number of 3. Inode numbers 0 and 1 are not used. File inode numbers can be seen by specifying the -i option to ls command. It is self contained. There are no dependencies between one filesystem and any other. The directories have specific purposes and generally hold the same types of information for easily locating files. Following are the directories that exist on the major versions of Unix: Directory / /bin Description This is the root directory which should contain only the directories needed at the top level of the file structure. This is where the executable files are located. They are available to all user. TUTORIALS POINT Simply Easy Learning
dev /etc /lib /boot /home /mnt /proc /tmp /usr /var /sbin These are device drivers. Supervisor directory commands, configuration files, disk configuration files, valid user lists, groups, ethernet, hosts, where to send critical messages. Contains shared library files and sometimes other kernel-related files. Contains files for booting the system. Contains the home directory for users and other accounts. Used to mount other temporary file systems, such as cdrom and floppy for the CD-ROM drive and floppy diskette drive, respectively Contains all processes marked as a file by process number or other information that is dynamic to the system. Holds temporary files used between system boots Used for miscellaneous purposes, or can be used by many users. Includes administrative commands, shared files, library files, and others Typically contains variable-length files such as log and print files and any other type of file that may contain a variable amount of data Contains binary (executable) files, usually for system administration. For examplefdisk and ifconfig utlities. /kernel Contains kernel files Navigating the File System: Now that you understand the basics of the file system, you can begin navigating to the files you need. The following are commands you'll use to navigate the system: Command cat filename cd dirname cp file1 file2 file filename find filename dir head filename less filename ls dirname mkdir dirname more filename mv file1 file2 pwd rm filename rmdir dirname Description Displays a filename. Moves you to the directory identified. Copies one file/directory to specified location. Identifies the file type (binary, text, etc). Finds a file/directory. Shows the beginning of a file. Browses through a file from end or beginning. Shows the contents of the directory specified. Creates the specified directory. Browses through a file from beginning to end. Moves the location of or renames a file/directory. Shows the current directory the user is in. Removes a file. Removes a directory. TUTORIALS POINT Simply Easy Learning
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Unix Tutorial
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ABOUT THE TUTORIAL Unix Tutorial UN
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Renaming Directories: .............
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Extended Shell Scripts: ...........
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Example: ..........................
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Trapping Signals: .................
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The main concept that unites all ve
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New UNIX password:******* Retype ne
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CHAPTER 2 Unix File Management All
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Displays all the files whose name s
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4. Fourth Column: represents file n
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CHAPTER 3 Unix Directories Adirecto
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Creates the directories docs and pu
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CHAPTER 4 Unix File Permission Setu
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$ls -l testfile -rw-rwxrwx 1 amrood
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The SUID and SGID bits will appear
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Note - The shell initialization pro
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The default secondary prompt is > (
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CHAPTER 6 Java Basic Utilities So f
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laserp-574 grace 82744 Nov 7 11:28
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CHAPTER 7 Unix Pipes and Filters Yo
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This pipe sorts all files in your d
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The process runs in the foreground,
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$kill -9 6738 Terminated Parent and
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CHAPTER 9 Unix Communication When y
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prompt on Turns prompt on. Dir List
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No Plan. Check all the logged in us
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~ ~ ~ ~ ~ ~ ~ ~ "testfile" [New Fil
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Command CTRL+d CTRL+d CTRL+f CTRL+u
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^G U U J Press CNTRL and G keys at
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IMPORTANT: Here are the key points
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POSIX shell ( sh) The different C-t
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CHAPTER 12 Unix- Using Variables Av
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NAME="Zara Ali" unset NAME echo $NA
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Command-Line Arguments: The command
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CHAPTER 14 Unix - Using Arrays Ashe
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CHAPTER 15 Unix - Basic Operators T
Page 75 and 76: val=`expr $b / $a` echo "b / a : $v
Page 77 and 78: else echo "$a -ge $b: a is not grea
Page 79 and 80: != Checks if the value of two opera
Page 81 and 82: ] is true. -x file Check if file is
Page 83 and 84: Right shift == String comparison fo
Page 85 and 86: -r file Checks if file is readable
Page 87 and 88: Example: #!/bin/sh a=10 b=20 if [ $
Page 89 and 90: There is only one form of case...es
Page 91 and 92: CHAPTER 17 Unix - Shell Loops Loops
Page 93 and 94: done This will produce following re
Page 95 and 96: 4) juice 5) appe 6) all 7) none #?
Page 97 and 98: CHAPTER 18 Unix - Loop Control So f
Page 99 and 100: 1 0 1 5 The continue statement: The
Page 101 and 102: \n new line \r carriage return \t h
Page 103 and 104: CHAPTER 20 Unix - Quoting Mechanism
Page 105 and 106: The Double Quotes: Try to execute t
Page 107 and 108: CHAPTER 21 Unix - IO Redirections M
Page 109 and 110: EOF 3 $ This is a simple lookup pro
Page 111 and 112: CHAPTER 22 Unix - Shell Functions F
Page 113 and 114: echo "Return value is $ret" This wo
Page 115 and 116: CHAPTER 23 Unix - Manpage Help All
Page 117 and 118: CHAPTER 24 Unix - Regular Expressio
Page 119 and 120: Try out the following address range
Page 121 and 122: sys:x:3:3:sys:/dev:/bin/sh sync:x:4
Page 123 and 124: [0-9] Matches a single number [a-zA
Page 125: (555)555-1213 (555)555-1214 (666)55
Page 129 and 130: $du -h /etc 5k /etc/cron.d 63k /etc
Page 131 and 132: CHAPTER 26 Unix - User Administrati
Page 133 and 134: $ groupdel developer This removes o
Page 135 and 136: CHAPTER 27 Unix - System Performanc
Page 137 and 138: CHAPTER 28 Unix - System Logging Un
Page 139 and 140: The combination of facilities and l
Page 141 and 142: Unix - Signals and Traps CHAPTER 29
Page 143 and 144: Trapping these signals is quite eas
Page 145 and 146: CHAPTER 30 Unix - Useful Commands T
Page 147 and 148: Ispell Emacs ex, edit Emacs Emacs C
Page 149 and 150: Command Dbx Gdb Make Nm Size Strip
Page 151 and 152: Reset Reset terminal mode Script Ke
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