Advanced Bash−Scripting Guide

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Advanced Bash−Scripting Guide echo "a (after a++) = $a" (( a−− )) # Post−decrement 'a', C−style. echo "a (after a−−) = $a" (( ++a )) # Pre−increment 'a', C−style. echo "a (after ++a) = $a" (( −−a )) # Pre−decrement 'a', C−style. echo "a (after −−a) = $a" echo (( t = a
Chapter 10. Loops and Branches Operations on code blocks are the key to structured, organized shell scripts. Looping and branching constructs provide the tools for accomplishing this. 10.1. Loops A loop is a block of code that iterates (repeats) a list of commands as long as the loop control condition is true. for loops for (in) This is the basic looping construct. It differs significantly from its C counterpart. for arg in [list] do command(s)... done During each pass through the loop, arg takes on the value of each successive variable in the list. for arg in "$var1" "$var2" "$var3" ... "$varN" # In pass 1 of the loop, $arg = $var1 # In pass 2 of the loop, $arg = $var2 # In pass 3 of the loop, $arg = $var3 # ... # In pass N of the loop, $arg = $varN # Arguments in [list] quoted to prevent possible word splitting. The argument list may contain wild cards. If do is on same line as for, there needs to be a semicolon after list. for arg in [list] ; do Example 10−1. Simple for loops #!/bin/bash # List the planets. for planet in Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto do echo $planet done echo # Entire 'list' enclosed in quotes creates a single variable. Chapter 10. Loops and Branches 103
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Advanced Bash−Scripting Guide An
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Chapter 1. Why Shell Programming? A
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Chapter 2. Starting Off With a Sha
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Chapter 3. Special Characters Speci
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# Sometimes, though, you get: # 11
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The "−" can be used to pipe stdou
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change the behavior of the terminal
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Chapter 4. Introduction to Variable
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Advanced Bash−Scripting Guide Exa
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Advanced Bash−Scripting Guide MIN
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The shift command reassigns the pos
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Example 5−1. Echoing Weird Variab
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(cd /source/directory && tar cf −
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true # the "true" builtin. echo "ex
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if [[ −e $file ]] then echo "Pass
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Advanced Bash−Scripting Guide −
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7.3. Comparison operators (binary)
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exit $E_CHANGED_MIND ;; *) echo "De
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The multiplication operator must be
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echo Number of digits at the beginn
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Outputs very verbose timing statist
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This line occurs three times. This
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# List all the users in /etc/passwd
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Advanced Bash−Scripting Guide # r
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Advanced Bash−Scripting Guide gre
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The −d option deletes a range of
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# Delete CR and write to new file.
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mailto Similar to the mail command,
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[ ${NETWORKING} = "no" ] && exit 0
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chroot Advanced Bash−Scripting Gu
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Chapter 15. Arithmetic Expansion Ar
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Advanced Bash−Scripting Guide # T
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# Saves stdin. Advanced Bash−Scri
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Advanced Bash−Scripting Guide 16.
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Chapter 17. Here Documents A here d
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Example 17−11. A self−documenti
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Part 4. Advanced Topics At this poi
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"Sed & Awk", by Dougherty and Robbi
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Chapter 20. Subshells Running a she
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# Range: 0 − 200 # It's crude, bu
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# grep PATTERN /etc/passwd | awk
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Advanced Bash−Scripting Guide # Y
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Chapter 25. List Constructs The "an
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# AND LIST executes on true, OR LIS
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echo ${colors[$index]} let "index =
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# Replace all matching wildcarded s
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Advanced Bash−Scripting Guide Cop
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fi let "t += $i " Primes[t]=$NON_PR
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Advanced Bash−Scripting Guide # =
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# −−−−−−−−− # 1)
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Chapter 28. /dev and /proc A Linux
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Advanced Bash−Scripting Guide # A
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Chapter 30. Debugging The Bash shel
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4. Advanced Bash−Scripting Guide
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Chapter 31. Options Options are set
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Chapter 32. Gotchas Turandot: Gli e
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command1 2> − | command2 # Trying
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echo "one two three" | read a b c #
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Chapter 33. Scripting With Style Ge
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Advanced Bash−Scripting Guide tpu
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#!/bin/bash # color−echo.sh: Echo
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34.7. Assorted Tips Advanced Bash
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Advanced Bash−Scripting Guide the
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Advanced Bash−Scripting Guide •
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# agram.sh: Playing games with anag
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Chapter 35. Bash, version 2 The cur
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1−56592−580−7). This is the s
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Bibliography Edited by Peter Dennin
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Advanced Bash−Scripting Guide * A
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Mark Komarinski's Printing−Usage
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let "row = $r" # Count center row o
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next_gen "$Cur" let "generation +=
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[−c localdirectory] [−m filepat
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Advanced Bash−Scripting Guide #:d
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# ListDirectory "FileGlob" "Field
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Advanced Bash−Scripting Guide # I
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The md5sum program is documented as
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Note: 'mount −l' does return the
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Advanced Bash−Scripting Guide dec
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Appendix B. A Sed and Awk Micro−P
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Advanced Bash−Scripting Guide /GU
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Advanced Bash−Scripting Guide Tha
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Appendix D. A Detailed Introduction
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Appendix E. Localization Localizati
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Appendix F. History Commands The Ba
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Appendix H. Converting DOS Batch Fi
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Advanced Bash−Scripting Guide XCO
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Appendix I. Exercises I.1. Analyzin
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Lottery Numbers One type of lottery
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Advanced Bash−Scripting Guide Usi
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Advanced Bash−Scripting Guide and
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[33] This is actually a script adap
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# Thanks to Stephane Chazelas for p
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