Advanced Bash−Scripting Guide

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Advanced Bash−Scripting Guide fi done < "$Filename" > "$Savefile" # Redirects stdin to file $Filename, # ^^^^^^^^^^^^^^^^^^^^^^^^^^^ and saves it to backup file. exit 0 Example 16−9. Redirected if/then test #!/bin/bash if [ −z "$1" ] then Filename=names.data else Filename=$1 fi # Default, if no filename specified. TRUE=1 if [ "$TRUE" ] # if true and if : also work. then read name echo $name fi
Advanced Bash−Scripting Guide 16.3. Applications Clever use of I/O redirection permits parsing and stitching together snippets of command output (see Example 11−6). This permits generating report and log files. Example 16−11. Logging events #!/bin/bash # logevents.sh, by Stephane Chazelas. # Event logging to a file. # Must be run as root (for write access in /var/log). ROOT_UID=0 E_NOTROOT=67 # Only users with $UID 0 have root privileges. # Non−root exit error. if [ "$UID" −ne "$ROOT_UID" ] then echo "Must be root to run this script." exit $E_NOTROOT fi FD_DEBUG1=3 FD_DEBUG2=4 FD_DEBUG3=5 # Uncomment one of the two lines below to activate script. # LOG_EVENTS=1 # LOG_VARS=1 log() # Writes time and date to log file. { echo "$(date) $*" >&7 # This *appends* the date to the file. # See below. } case $LOG_LEVEL in 1) exec 3>&2 4> /dev/null 5> /dev/null;; 2) exec 3>&2 4>&2 5> /dev/null;; 3) exec 3>&2 4>&2 5>&2;; *) exec 3> /dev/null 4> /dev/null 5> /dev/null;; esac FD_LOGVARS=6 if [[ $LOG_VARS ]] then exec 6>> /var/log/vars.log else exec 6> /dev/null fi # Bury output. FD_LOGEVENTS=7 if [[ $LOG_EVENTS ]] then Chapter 16. I/O Redirection 251
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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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Advanced Bash−Scripting Guide Eac
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Chapter 3. Special Characters Speci
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Advanced Bash−Scripting Guide \ /
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Advanced Bash−Scripting Guide * ?
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Advanced Bash−Scripting Guide ech
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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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Advanced Bash−Scripting Guide Thi
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Advanced Bash−Scripting Guide if
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if [[ −e $file ]] then echo "Pass
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Advanced Bash−Scripting Guide −
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7.3. Comparison operators (binary)
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Example 7−5. arithmetic and strin
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Chapter 8. Operations and Related T
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Advanced Bash−Scripting Guide ! ^
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Advanced Bash−Scripting Guide let
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Part 3. Beyond the Basics Table of
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$EDITOR the default editor invoked
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Advanced Bash−Scripting Guide (Th
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Advanced Bash−Scripting Guide #!/
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Example 9−2. Timed Input Advanced
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Advanced Bash−Scripting Guide fi
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echo 'IFS=":", using "$@"' c=0 for
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Advanced Bash−Scripting Guide #+
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Advanced Bash−Scripting Guide use
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echo '${var1#$pattern1} =' "${var1#
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t=${path_name%/*.*} # Same effect a
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Chapter 10. Loops and Branches Oper
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Advanced Bash−Scripting Guide # T
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Advanced Bash−Scripting Guide OUT
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As is the case with for/in loops, p
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This construct tests for a conditio
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Advanced Bash−Scripting Guide ###
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Advanced Bash−Scripting Guide don
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# Accept upper or lowercase input.
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Advanced Bash−Scripting Guide a=`
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# May need to also press ENTER if a
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Advanced Bash−Scripting Guide The
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Advanced Bash−Scripting Guide ret
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Advanced Bash−Scripting Guide Com
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Advanced Bash−Scripting Guide ena
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cat, tac # Burn the CDR. cdrecord
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Advanced Bash−Scripting Guide 12.
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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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Advanced Bash−Scripting Guide gzi
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Advanced Bash−Scripting Guide No
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mailto Similar to the mail command,
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Advanced Bash−Scripting Guide int
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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 net
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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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Advanced Bash−Scripting Guide whi
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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 See
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Advanced Bash−Scripting Guide # T
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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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Advanced Bash−Scripting Guide # R
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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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Advanced Bash−Scripting Guide #+
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Advanced Bash−Scripting Guide pad
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Advanced Bash−Scripting Guide arr
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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 # =
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Advanced Bash−Scripting Guide } z
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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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Advanced Bash−Scripting Guide } X
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Advanced Bash−Scripting Guide pow
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Advanced Bash−Scripting Guide *)
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Advanced Bash−Scripting Guide com
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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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