Unix Tutorial

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echo "File size is zero" else echo "File size is not zero" fi if [ -e $file ] then echo "File exists" else echo "File does not exist" fi This would produce following result: File has read access File has write permission File has execute permission File is an ordinary file This is not a directory File size is zero File exists There are following points to note down: There must be spaces between operators and expressions for example 2+2 is not correct, where as it should be written as 2 + 2. if...then...else...fi statement is a decision making statement which has been explained in next chapter. C Shell Operators: This lists down all the operators available in C Shell. Here most of the operators are very similar to what we have in C Programming language. Operators are listed in order of decreasing precedence: Arithmetic and Logical Operators: Operator Description ( ) Change precedence ~ 1's complement ! Logical negation * Multiply / Divide % Modulo + Add - Subtract
Right shift == String comparison for equality != String comparison for non equality =~ Pattern matching & ^ Bitwise "and" Bitwise "exclusive or" | Bitwise "inclusive or" && Logical "and" || Logical "or" ++ Increment -- Decrement = Assignment *= Multiply left side by right side and update left side /= Divide left side by right side and update left side += Add left side to right side and update left side -= Subtract left side from right side and update left side ^= "Exclusive or" left side to right side and update left side %= Divide left by right side and update left side with remainder File Test Operators: There are following operators to test various properties associated with a <strong>Unix</strong> file. Operator Description -r file Checks if file is readable if yes then condition becomes true. -w file Check if file is writable if yes then condition becomes true. -x file Check if file is execute if yes then condition becomes true. -f file Check if file is an ordinary file as opposed to a directory or special file if yes then condition becomes true. -z file Check if file has size greater than 0 if yes then condition becomes true. -d file Check if file is a directory if yes then condition becomes true. -e file Check if file exists. Is true even if file is a directory but exists. -o file Check if user owns the file. It returns true if user is the owner of the file. 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
Page 31 and 32: The SUID and SGID bits will appear
Page 33 and 34: Note - The shell initialization pro
Page 35 and 36: The default secondary prompt is > (
Page 37 and 38: CHAPTER 6 Java Basic Utilities So f
Page 39 and 40: laserp-574 grace 82744 Nov 7 11:28
Page 41 and 42: CHAPTER 7 Unix Pipes and Filters Yo
Page 43 and 44: This pipe sorts all files in your d
Page 45 and 46: The process runs in the foreground,
Page 47 and 48: $kill -9 6738 Terminated Parent and
Page 49 and 50: CHAPTER 9 Unix Communication When y
Page 51 and 52: prompt on Turns prompt on. Dir List
Page 53 and 54: No Plan. Check all the logged in us
Page 55 and 56: ~ ~ ~ ~ ~ ~ ~ ~ "testfile" [New Fil
Page 57 and 58: Command CTRL+d CTRL+d CTRL+f CTRL+u
Page 59 and 60: ^G U U J Press CNTRL and G keys at
Page 61 and 62: IMPORTANT: Here are the key points
Page 63 and 64: POSIX shell ( sh) The different C-t
Page 65 and 66: CHAPTER 12 Unix- Using Variables Av
Page 67 and 68: NAME="Zara Ali" unset NAME echo $NA
Page 69 and 70: Command-Line Arguments: The command
Page 71 and 72: CHAPTER 14 Unix - Using Arrays Ashe
Page 73 and 74: 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: ] is true. -x file Check if file is
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 and 126: (555)555-1213 (555)555-1214 (666)55
Page 127 and 128: dev /etc /lib /boot /home /mnt /pro
Page 129 and 130: $du -h /etc 5k /etc/cron.d 63k /etc
Page 131 and 132: CHAPTER 26 Unix - User Administrati
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$ groupdel developer This removes o
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CHAPTER 27 Unix - System Performanc
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CHAPTER 28 Unix - System Logging Un
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The combination of facilities and l
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Unix - Signals and Traps CHAPTER 29
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Trapping these signals is quite eas
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CHAPTER 30 Unix - Useful Commands T
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Ispell Emacs ex, edit Emacs Emacs C
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Command Dbx Gdb Make Nm Size Strip
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Reset Reset terminal mode Script Ke
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