Bash-Beginners-Guide

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# files are moved. # Might be something for cron (if slightly adapted) to execute weekly or # monthly. ARCHIVENR=`date +%Y%m%d` DESTDIR="$PWD/archive-$ARCHIVENR" mkdir "$DESTDIR" # using quotes to catch file names containing spaces, using read -d for more # fool-proof usage: find "$PWD" -type f -a -mtime +5 | while read -d $'\000' file do gzip "$file"; mv "$file".gz "$DESTDIR" echo "$file archived" done Files are compressed before they are moved into the archive directory. 9.5. Break and continue 9.5.1. The break built-in Bash Guide for Beginners The break statement is used to exit the current loop before its normal ending. This is done when you don't know in advance how many times the loop will have to execute, for instance because it is dependent on user input. The example below demonstrates a while loop that can be interrupted. This is a slightly improved version of the wisdom.sh script from Section 9.2.2.3. #!/bin/bash # This script provides wisdom # You can now exit in a decent way. FORTUNE=/usr/games/fortune while true; do echo "On which topic do you want advice?" echo "1. politics" echo "2. startrek" echo "3. kernelnewbies" echo "4. sports" echo "5. bofh-excuses" echo "6. magic" echo "7. love" echo "8. literature" echo "9. drugs" echo "10. education" echo echo -n "Enter your choice, or 0 for exit: " read choice echo case $choice in 1) $FORTUNE politics Chapter 9. Repetitive tasks 114
;; 2) $FORTUNE startrek ;; 3) $FORTUNE kernelnewbies ;; 4) echo "Sports are a waste of time, energy and money." echo "Go back to your keyboard." echo -e "\t\t\t\t -- \"Unhealthy is my middle name\" Soggie." ;; 5) $FORTUNE bofh-excuses ;; 6) $FORTUNE magic ;; 7) $FORTUNE love ;; 8) $FORTUNE literature ;; 9) $FORTUNE drugs ;; 10) $FORTUNE education ;; 0) echo "OK, see you!" break ;; *) echo "That is not a valid choice, try a number from 0 to 10." ;; esac done Mind that break exits the loop, not the script. This can be demonstrated by adding an echo command at the end of the script. This echo will also be executed upon input that causes break to be executed (when the user types "0"). In nested loops, break allows for specification of which loop to exit. See the Bash info pages for more. 9.5.2. The continue built-in Bash Guide for Beginners The continue statement resumes iteration of an enclosing for, while, until or select loop. When used in a for loop, the controlling variable takes on the value of the next element in the list. When used in a while or until construct, on the other hand, execution resumes with TEST-COMMAND at the top of the loop. Chapter 9. Repetitive tasks 115
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Bash Guide for Beginners Machtelt G
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Bash Guide for Beginners Table of C
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Bash Guide for Beginners Table of C
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Table of Contents Glossary C.......
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Introduction 1. Why this guide? The
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Revision 1.6 2005-03-01 Revised by:
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Bash Guide for Beginners See Chapte
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Bash Guide for Beginners mia:~> cat
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Bash Guide for Beginners When invok
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More information about the file des
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Built-in commands are necessary to
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• Brace expansion • Tilde expan
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A number of methods can be used; on
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Bash Guide for Beginners stop in ea
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Chapter 2. Writing and debugging sc
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the documentation of your favorite
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Bash Guide for Beginners Comments a
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Bash Guide for Beginners + set +x I
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Chapter 3. The Bash environment In
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Bash Guide for Beginners local pid
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MOZILLA_FIVE_HOME=/usr/lib/mozilla
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Bash Guide for Beginners franky ~>
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the GNU Awk programming language is
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Bash Guide for Beginners 3.2.4. Res
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LINES MACHTYPE MAILCHECK OLDPWD OPT
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two is the second positional parame
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Bash Guide for Beginners 3.3.1. Why
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A correctly-formed brace expansion
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Bash Guide for Beginners If the sub
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of the whitespace characters "space
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Bash Guide for Beginners /dev/hda5
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Bash Guide for Beginners 3.7. Summa
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Two regular expressions may be conc
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LABEL=/ / ext3 defaults 1 1 If this
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cathy ~> ls -ld [[:digit:]]* drwxrw
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Page 73 and 74: sandy ~> sed -n '/a text/,/This/p'
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Page 155 and 156: cd Change directory. cdp/cdplay An
Page 157 and 158: Bash Guide for Beginners gimp grep
Page 159 and 160: Send and receive mail. man Read man
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Page 165 and 166: Index A aliases Section 3.5.1 ANSI-
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Bash Guide for Beginners vi(m) Sect
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