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Unix Shell Scripting Basics
 

Unix Shell Scripting Basics

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Unix Shell Scripting Basics Unix Shell Scripting Basics Presentation Transcript

  • UNIX Shell-Scripting Basics
  • Agenda
    • What is a shell? A shell script?
    • Introduction to bash
    • Running Commands
    • Applied Shell Programming
  • What is a shell?
    • %
  • What is a shell?
    • /bin/bash
  • What is a shell?
    • #!/bin/bash
  • What is a shell? INPUT shell OUTPUT ERROR
  • What is a shell?
    • Any Program
    • But there are a few popular shells…
  • Bourne Shells
    • /bin/sh
    • /bin/bash “Bourne-Again Shell”
    Steve Bourne
  • Other Common Shells
    • C Shell ( /bin/csh )
    • Turbo C Shell ( /bin/tcsh )
    • Korn Shell ( /bin/ksh )
  • An aside: What do I mean by /bin ?
    • C Shell ( /bin/csh )
    • Turbo C Shell ( /bin/tcsh )
    • Korn Shell ( /bin/ksh )
  • An aside: What do I mean by /bin ?
    • /bin, /usr/bin, /usr/local/bin
    • /sbin, /usr/sbin, /usr/local/sbin
    • /tmp
    • /dev
    • /home/borwicjh
  • What is a Shell Script?
    • A Text File
    • With Instructions
    • Executable
  • What is a Shell Script?
    • % cat > hello.sh <<MY_PROGRAM
    • #!/bin/sh
    • echo ‘Hello, world’
    • MY_PROGRAM
    • % chmod +x hello.sh
    • % ./hello.sh
    • Hello, world
  • What is a Shell Script? A Text File
    • % cat > hello.sh <<MY_PROGRAM
    • #!/bin/sh
    • echo ‘Hello, world’
    • MY_PROGRAM
    • % chmod +x hello.sh
    • % ./hello.sh
    • Hello, world
  • An aside: Redirection
    • cat > /tmp/myfile
    • cat >> /tmp/myfile
    • cat 2> /tmp/myerr
    • cat < /tmp/myinput
    • cat <<INPUT Some input INPUT
    • cat > /tmp/x 2>&1
    0 1 2 INPUT env OUTPUT ERROR
  • What is a Shell Script? How To Run
    • % cat > hello.sh <<MY_PROGRAM
    • #!/bin/sh
    • echo ‘Hello, world’
    • MY_PROGRAM
    • % chmod +x hello.sh
    • % ./hello.sh
    • Hello, world
  • What is a Shell Script? What To Do
    • % cat > hello.sh <<MY_PROGRAM
    • #!/bin/sh
    • echo ‘Hello, world’
    • MY_PROGRAM
    • % chmod +x hello.sh
    • % ./hello.sh
    • Hello, world
  • What is a Shell Script? Executable
    • % cat > hello.sh <<MY_PROGRAM
    • #!/bin/sh
    • echo ‘Hello, world’
    • MY_PROGRAM
    • % chmod +x hello.sh
    • % ./hello.sh
    • Hello, world
  • What is a Shell Script? Running it
    • % cat > hello.sh <<MY_PROGRAM
    • #!/bin/sh
    • echo ‘Hello, world’
    • MY_PROGRAM
    • % chmod +x hello.sh
    • % ./hello.sh
    • Hello, world
  • Finding the program: PATH
    • % ./hello.sh
    • echo vs. /usr/bin/echo
    • % echo $PATH /bin:/usr/bin:/usr/local/bin: /home/borwicjh/bin
    • % which echo /usr/bin/echo
  • Variables and the Environment
    • % hello.sh
    • bash: hello.sh: Command not found
    • % PATH=“$PATH:.”
    • % hello.sh
    • Hello, world
  • An aside: Quoting
    • % echo ‘ $USER ’
    • $USER
    • % echo “ $USER ”
    • borwicjh
    • % echo “ ” ”
    • % echo “deacnet sct”
    • deacnetsct
    • % echo ‘ ” ’
  • Variables and the Environment
    • % env
    • […variables passed to sub-programs…]
    • % NEW_VAR=“Yes”
    • % echo $NEW_VAR
    • Yes
    • % env
    • […PATH but not NEW_VAR…]
    • % export NEW_VAR
    • % env
    • […PATH and NEW_VAR…]
  • Welcome to Shell Scripting! Shebang! The Environment PATH Input, Output, and Error chmod
  • How to Learn
    • man
      • man bash
      • man cat
      • man man
    • man –k
      • man –k manual
    • Learning the Bash Shell , 2 nd Ed.
    • “ Bash Reference” Cards
    • http://www.tldp.org/LDP/abs/html/
  • Introduction to bash
  • Continuing Lines:
    • % echo This
    • Is
    • A
    • Very
    • Long
    • Command Line
    • This Is A Very Long Command Line
    • %
  • Exit Status
    • $?
    • 0 is True
    • % ls /does/not/exist
    • % echo $?
    • 1
    • % echo $?
    • 0
  • Exit Status: exit
    • % cat > test.sh <<_TEST_
    • exit 3
    • _TEST_
    • % chmod +x test.sh
    • % ./test.sh
    • % echo $?
    • 3
  • Logic: test
    • % test 1 -lt 10
    • % echo $?
    • 0
    • % test 1 == 10
    • % echo $?
    • 1
  • Logic: test
    • test
    • [ ]
      • [ 1 –lt 10 ]
    • [[ ]]
      • [[ “this string” =~ “this” ]]
    • (( ))
      • (( 1 < 10 ))
  • Logic: test
    • [ -f /etc/passwd ]
    • [ ! –f /etc/passwd ]
    • [ -f /etc/passwd –a –f /etc/shadow ]
    • [ -f /etc/passwd –o –f /etc/shadow ]
  • An aside: $(( )) for Math
    • % echo $(( 1 + 2 ))
    • 3
    • % echo $(( 2 * 3 ))
    • 6
    • % echo $(( 1 / 3 ))
    • 0
  • Logic: if
    • if something
    • then
    • :
    • # “elif” a contraction of “else if”:
    • elif something-else
    • then
    • :
    • else
    • then
    • :
    • fi
  • Logic: if
    • if [ $USER –eq “borwicjh” ]
    • then
    • :
    • # “elif” a contraction of “else if”:
    • elif ls /etc/oratab
    • then
    • :
    • else
    • then
    • :
    • fi
  • Logic: if
    • # see if a file exists
    • if [ -e /etc/passwd ]
    • then
    • echo “/etc/passwd exists”
    • else
    • echo “/etc/passwd not found!”
    • fi
  • Logic: for
    • for i in 1 2 3
    • do
    • echo $i
    • done
  • Logic: for
    • for i in /*
    • do
    • echo “Listing $i:”
    • ls -l $i
    • read
    • done
  • Logic: for
    • for i in /*
    • do
    • echo “Listing $i:”
    • ls -l $i
    • read
    • done
  • Logic: for
    • for i in /*
    • do
    • echo “Listing $i:”
    • ls -l $i
    • read
    • done
  • Logic: C-style for
    • for (( expr1 ;
    • expr2 ;
    • expr3 ))
    • do
    • list
    • done
  • Logic: C-style for
    • LIMIT=10
    • for (( a=1 ;
    • a<=LIMIT ;
    • a++ ))
    • do
    • echo –n “$a ”
    • done
  • Logic: while
    • while something
    • do
    • :
    • done
  • Logic: while
    • a=0; LIMIT=10
    • while [ &quot;$a&quot; -lt &quot;$LIMIT&quot; ]
    • do
    • echo -n &quot;$a ”
    • a=$(( a + 1 ))
    • done
  • Counters
    • COUNTER=0
    • while [ -e “$FILE.COUNTER” ]
    • do
    • COUNTER=$(( COUNTER + 1))
    • done
    • Note: race condition
  • Reusing Code: “Sourcing”
    • % cat > /path/to/my/passwords <<_PW_
    • FTP_USER=“sct”
    • _PW_
    • % echo $FTP_USER
    • % . /path/to/my/passwords
    • % echo $FTP_USER
    • sct
    • %
  • Variable Manipulation
    • % FILEPATH=/path/to/my/output.lis
    • % echo $FILEPATH
    • /path/to/my/output.lis
    • % echo ${FILEPATH %.lis }
    • /path/to/my/output
    • % echo ${FILEPATH #*/ }
    • path/to/my/output.lis
    • % echo ${FILEPATH ##*/ }
    • output.lis
    • It takes a long time to become a bash guru…
  • Running Programs
  • Reasons for Running Programs
    • Check Return Code
      • $?
    • Get Job Output
      • OUTPUT=`echo “Hello”`
      • OUTPUT=$(echo “Hello”)
    • Send Output Somewhere
      • Redirection: < , >
      • Pipes
  • Pipes
    • Lots of Little Tools
    • echo “Hello” |
    • wc -c
    INPUT echo OUTPUT ERROR 0 1 2 INPUT wc OUTPUT ERROR 0 1 2 A Pipe!
  • Email Notification
    • % echo “Message” |
    • mail –s “Here’s your message”
    • [email_address]
  • Dates
    • % DATESTRING=`date +%Y%m%d`
    • % echo $DATESTRING
    • 20060125
    • % man date
  • FTP the Hard Way
    • ftp –n –u server.wfu.edu <<_FTP_
    • user username password
    • put FILE
    • _FTP_
  • FTP with wget
    • wget ftp://user:pass@server.wfu.edu/file
    • wget –r ftp://user:pass@server.wfu.edu/dir/
  • FTP with curl
    • curl –T upload-file
    • -u username:password
    • ftp://server.wfu.edu/dir/file
  • Searching: grep
    • % grep rayra /etc/passwd
    • % grep –r rayra /etc
    • % grep –r RAYRA /etc
    • % grep –ri RAYRA /etc
    • % grep –rli rayra /etc
  • Searching: find
    • % find /home/borwicjh
    • -name ‘*.lis’
    • [all files matching *.lis]
    • % find /home/borwicjh
    • -mtime -1 –name ‘*.lis’
    • [*.lis, if modified within 24h]
    • % man find
  • Searching: locate
    • % locate .lis
    • [files with .lis in path]
    • % locate log
    • [also finds “/var/log/messages”]
  • Applied Shell Programming
  • Make Your Life Easier
    • TAB completion
    • Control+R
    • history
    • cd -
    • Study a UNIX Editor
  • pushd/popd
    • % cd /tmp
    • % pushd /var/log
    • /var/log /tmp
    • % cd ..
    • % pwd
    • /var
    • % popd
    • /tmp
  • Monitoring processes
    • ps
    • ps –ef
    • ps –u oracle
    • ps –C sshd
    • man ps
  • “DOS” Mode Files
    • #!/usr/bin/bash^M
    • FTP transfer in ASCII, or
    • dos2unix infile > outfile
  • sqlplus
    • JOB=“ZZZTEST”
    • PARAMS=“ZZZTEST_PARAMS”
    • PARAMS_USER=“BORWICJH”
    • sqlplus $BANNER_USER/$BANNER_PW << _EOF_
    • set serveroutput on
    • set sqlprompt &quot;&quot;
    • EXECUTE WF_SATURN.FZ_Get_Parameters('$JOB', '$PARAMS', '$PARAMS_USER');
    • _EOF_
  • sqlplus
    • sqlplus $USER/$PASS @$FILE_SQL
    • $ARG1 $ARG2 $ARG3
    • if [ $? –ne 0 ]
    • then
    • exit 1
    • fi
    • if [ -e /file/sql/should/create ]
    • then
    • […use SQL-created file…]
    • fi
    • Ask Amy Lamy! 
  • Passing Arguments
    • % cat > test.sh <<_TEST_
    • echo “Your name is $1 $2 ”
    • _TEST_
    • % chmod +x test.sh
    • % ./test.sh John Borwick ignore-this
    • Your name is John Borwick
  • INB Job Submission Template
    • $1 : user ID
    • $2 : password
    • $3 : one-up number
    • $4 : process name
    • $5 : printer name
    • % /path/to/your/script $UI $PW
    • $ONE_UP $JOB $PRNT
  • Scheduling Jobs
    • % crontab -l
    • 0 0 * * * daily-midnight-job.sh
    • 0 * * * * hourly-job.sh
    • * * * * * every-minute.sh
    • 0 1 * * 0 1AM-on-sunday.sh
    • % EDITOR=vi crontab –e
    • % man 5 crontab
  • It's Over!
  • Other Questions?
    • Shells and Shell Scripts
    • bash
    • Running Commands
    • bash and Banner in Practice