Copyright Sams Teach Yourself Shell Programming in 24 Hours

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Sams Teach Yourself Shell Programming in 24 Hours Contents Index Introduction Sections in this Chapter: Previous Chapter Next Chapter How This Book Is Organized Dedication Conventions Used in This Book Acknowledgments About the Author Previous Section Next Section Dedication For my grandmother, who taught me to love the English language. For my mother, who taught me to love programming languages. Sams Teach Yourself Shell Programming in 24 Hours Contents Index Introduction Sections in this Chapter: Previous Chapter Next Chapter How This Book Is Organized Dedication Conventions Used in This Book Acknowledgments About the Author Previous Section Next Section © Copyright Macmillan Computer Publishing. All rights reserved.
Sams Teach Yourself Shell Programming in 24 Hours Contents Index Introduction Sections in this Chapter: Previous Chapter Next Chapter How This Book Is Organized Dedication Conventions Used in This Book Acknowledgments About the Author Previous Section Next Section Acknowledgments Writing a book on shell programming is a daunting task, due to the myriad of UNIX versions and shell versions that are available. Thanks to the work of my development editor Hugh Vandivier and my technical editor Aron Hsiao, I was able to make sure the book covered all the material completely and correctly. Their suggestions and comments have helped me enormously. In addition to the technical side of the book, many things about the publishing process were new to me. Thanks to my acquisitions editor Gretchen Ganser and my executive editor Jeff Koch for handling all of the editorial issues and patiently working with me to keep this book on schedule. I would also like to thank Jane Brownlow who got me started on this project. Working on a book takes a lot of time from work, as I found out. Thanks to the cooperation and understanding of my managers Pat Shriver and Larry Coryell, I was able to balance work and authoring. I know there is a thing called regular work, Pat. I'll get to it soon. I promise. I need to thank my parents; my brother, Srivathsa; and my aunt and uncle, Srinivasa and Suma; who put off family activities so that I could finish this book. I promise we'll go to Lake Tahoe next year. Also thanks to my cousin's wife, Katherine, who wanted to see her name in my book. Thanks to everyone else on the excellent team at Sams who worked on this book. Without their support, this book would not exist. Sams Teach Yourself Shell Programming in 24 Hours Contents Index Introduction Sections in this Chapter: Previous Chapter Next Chapter How This Book Is Organized Dedication Conventions Used in This Book Acknowledgments About the Author Previous Section Next Section © Copyright Macmillan Computer Publishing. All rights reserved.
Page 1 and 2: Sams Teach Yourself Shell Programmi
Page 3 and 4: ● Using Single Quotes ● Using D
Page 5 and 6: ● Questions Hour 20: Debugging
Page 9 and 10: ● Part I is an introduction to UN
Page 11 and 12: Many of the examples and the answer
Page 13: Sams Teach Yourself Shell Programmi
Page 17 and 18: $ date [ENTER] Wed Dec 9 08:49:13 P
Page 19 and 20: anga pts/0 Dec 9 08:49 $ Here, the
Page 23 and 24: The original UNIX shell was written
Page 25 and 26: There are three major versions of k
Page 31 and 32: example, when you execute the comma
Page 35 and 36: This executes the compound command
Page 37 and 38: chmod a+x ./logins Here you are usi
Page 41 and 42: Try using the man command to get mo
Page 49 and 50: Hidden Files So far you have used l
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Page 53 and 54: Numbering Lines The cat command als
Page 55 and 56: command $ wc -w .rhosts produces th
Page 59 and 60: produces the following error: cp: w
Page 61 and 62: m: work directory The two files are
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Sams Teach Yourself Shell Programmi
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name. Thus both of the following fi
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../docs/ch5.doc represents the file
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changes to the directory /usr/local
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If you specify several arguments in
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Sometimes when you want to create a
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$ cp -r docs /mnt/zip/backup cp: ca
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Removing Directories You can use tw
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$ ls -ld /home/ranga This produces
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You can see the relative path by us
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Sections in this Chapter: File Type
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The permission block for this file
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Here, expression is a statement of
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For example, if the directory pub c
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Restrictions The super user, root,
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Running the same ls command as in t
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Tip - Background Processes That Wri
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the fg command. By default, the pro
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dhorvath 6770 3662 2 10:35:45 pts/6
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By default, a process runs with the
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Process Identifier --The process id
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Variable Names The name of a variab
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Array Variables The Bourne shell, s
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$ band[2]=mike $ band[3]=gene Tip -
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Hour 7: Variables Sections in this
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uses internally. Users can modify t
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Here, command is the name of a comm
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$ ls ch??.doc to accomplish this. M
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© Copyright Macmillan Computer Pub
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is unset. Assigning a Default Value
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© Copyright Macmillan Computer Pub
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It now gives this error result: Hel
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Sections in this Chapter: Quoting w
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To the shell, one or more spaces or
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Quoting Regular Expression Wildcard
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fi list5 Both the elif and the else
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Here you have an elif statement tha
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Consider the following if statement
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If you were to use the - n option i
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else echo "An error was encountered
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1. First the test [ -z "$DTHOME" ]
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esac Here the string contained in $
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The execution of a while loop proce
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5 4 3 2 1 0 6 5 4 3 2 1 0 7 6 5 4 3
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2. If the exit status of command is
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for i in 0 1 2 3 4 5 6 7 8 9 do ech
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3. When the user enters a value, $R
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The continue Command The continue c
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If you want to list the contents of
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In this version, the basename comma
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USAGE="Usage: ´basename $0´ [-c|-
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uuencoding a file. For readers who
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fi fi echo $MSG You could simplify
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● Formatting escape sequences Emb
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Name User Name Sriranga ranga Sriva
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Table 13.2 Formatting Sequence Type
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printf "%-32s " "$i" if [ -d "$i" ]
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anga ttyp0 Oct 27 19:42 (:0.0) amma
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Say you need to send a list of phon
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"Miscellaneous Tools," I will show
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$ exec 4>fd4.out associates the fil
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command > file 2>&1 list > file 2>&
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when the while loop exits, the valu
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Note - The shell uses the value of
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This function has three important p
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} OLDIFS="$IFS" IFS=: # print each
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} # set the directory to pop to the
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index.html RCS humor misc downloads
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unix has several additional pieces
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pqops.c:/* Function to delete a nod
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Here I specified set2 as the space
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$ tr '!?":;\[\]{}(),.\t\n' ' ' < /h
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in 69 ' 65 the 389 to 164 of 127 No
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tr '[:classname:]' 'set2' Here clas
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single letters, whereas in awk the
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able was I, ere I saw elba Because
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By adding the ^ metacharacter as fo
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\$[0-9]*\.[0-9][0-9]\/[a-zA-Z]*/ If
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Here you list the name of a fruit a
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$ rm fruit_prices.txt.$$ Performing
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Fortunately, the s command provides
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lrwxrwxrwx 1 ranga users 8 Nov 27 1
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The original awk has remained almos
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Kiwi 22 Pineapple 35 Apple 78 All t
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Pineapple $1.29 35 REORDER Apple $0
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$ ls -l produces output formatted s
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The value that you assign a variabl
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x=x+1 In awk this can be written in
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the pattern specifies. To solve you
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awk -F: '{ ... }' The major differe
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identical to expressions you looked
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The basic syntax is do { actions }
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B:amount Here amount is the balance
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The OUTPUT variable contains the >
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: ${LINES:=24} ${TERM:?"TERM not se
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Sections in this Chapter: The eval
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eports/1998 The starting directory.
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find: -type Option The -type option
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find / -name alpha -size +50 -mtime
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18 quit $ obase=16 sets the output
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The default action for the signals
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fi Init() { printf "INFO: Initializ
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4. Wait for the program to finish e
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} if [ $? -eq 0 ] ; then echo "Sub-
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A third way of enabling debugging i
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Here the debugging mode is enabled
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if [ $YN = "y" ] ; then Making this
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$ /bin/sh -nv ./buggy2.sh the outpu
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Deleting old backups, please wait..
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If you do not type a response and p
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To deactivate debugging, use either
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3 MSG="hello" 4 echo_error $MSG Her
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echo "ERROR: File $MYFILE was not f
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previous call to this function. Aft
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} Before you look at some examples
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dev/hda1 1190014 664661 463867 59%
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The number returned is in kilobytes
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getUID() { id $1 | sed -e 's/(.*$//
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63 printf "$1 (y/n)? " 64 65 if [ -
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}' 171 # Args: $1 -> the command na
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Some UNIX versions implement a work
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24 printERROR "The source $1 is not
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easily modify the script to replace
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Hour 22: Problem Solving with Shell
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To maintain your address book, you
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produces two matches: Name: Srirang
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26 # enable erasing input 27 28 stt
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2. Based on user feedback, delete t
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73 promptYESNO "Delete this entry"
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MYADDRESSBOOK="$HOME/addressbook" i
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Here, options is one or more of the
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Now that you have looked at using t
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Abstraction is a technique used to
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warning: '-' deprecated; use 'ps au
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produce the same result if the curr
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The structure of the UNIX directory
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OLDPREFIX=aaa NEWPREFIX=bbb for FIL
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history (Korn/Bash) shows the most
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Sections in this Chapter: Reserved
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^ bitwise exclusive OR operation |
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Bash array initialization USERVAR=(
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order to fix problems. default beha
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minor number UNIX uses this to asso
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important parameters. This is usual
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Sections in this Chapter: Chapter 1
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USAGE="Usage: ´basename $0´ [-v]
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Appendix C: Quiz Answers Sections i
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awk -F: ' $1 == "B" { BAL=$NF ; nex
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} if [ $DEF_TOUT -ne 0 ] ; then sle
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Sections in this Chapter: Chapter 1
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} fi if [ ! -d "$1" ] ; then printE
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numeric variables, 1st pattern-spec
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wildcards, 1st Bourne shells. See s
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(colon), 1st character, 1st, 2nd, 3
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grep, 1st, 2nd line numbers, 1st li
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stty addperson script, 1st tail, 1s
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emoving temporary files, 1st displa
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mv command, 1st, 2nd rmdir command,
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interactive mode, 1st multiple inpu
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starting directory, 1st, 2nd findin
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installation scripts disk usage, 1s
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eak command, 1st, 2nd, 3rd continue
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mvdir.sh, 1st, 2nd, 3rd, 4th, 5th,
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edirection, 1st, 2nd appending to f
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[0-9]*, 1st percent sign (%) job nu
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profiles shell specific startup wit
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hardware type, 1st, 2nd improving,
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(standard error), 1st displaying me
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prompt, 1st, 2nd, 3rd, 4th quoting
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egp command, 1st -k option sort com
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