The document provides an introduction to UNIX shell scripting basics. It discusses what a shell and shell script are, how to run commands and write simple shell scripts using bash. It covers basics like variables, conditionals, loops, pipes and redirection to process inputs, outputs and errors when running programs from shell scripts.

1. UNIX Shell-Scripting Basics

2. Agenda What is a shell? A shell script? Introduction to bash Running Commands Applied Shell Programming

3. What is a shell? % ▌

4. What is a shell? /bin/bash

5. What is a shell? #!/bin/bash

6. What is a shell? INPUT shell OUTPUT ERROR

7. What is a shell? Any Program But there are a few popular shells…

8. Bourne Shells /bin/sh /bin/bash “Bourne-Again Shell” Steve Bourne

9. Other Common Shells C Shell ( /bin/csh ) Turbo C Shell ( /bin/tcsh ) Korn Shell ( /bin/ksh )

10. An aside: What do I mean by /bin ? C Shell ( /bin/csh ) Turbo C Shell ( /bin/tcsh ) Korn Shell ( /bin/ksh )

11. An aside: What do I mean by /bin ? /bin, /usr/bin, /usr/local/bin /sbin, /usr/sbin, /usr/local/sbin /tmp /dev /home/borwicjh

12. What is a Shell Script? A Text File With Instructions Executable

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. Variables and the Environment % hello.sh bash: hello.sh: Command not found % PATH=“$PATH:.” % hello.sh Hello, world

22. An aside: Quoting % echo ‘ $USER ’ $USER % echo “ $USER ” borwicjh % echo “ \” ” ” % echo “deacnet \\ sct” deacnet\sct % echo ‘ \” ’ \”

23. 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…]

24. Welcome to Shell Scripting! Shebang! The Environment PATH Input, Output, and Error chmod

25. 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/

26. Introduction to bash

27. Continuing Lines: \ % echo This \ Is \ A \ Very \ Long \ Command Line This Is A Very Long Command Line %

28. Exit Status $? 0 is True % ls /does/not/exist % echo $? 1 % echo $? 0

29. Exit Status: exit % cat > test.sh <<_TEST_ exit 3 _TEST_ % chmod +x test.sh % ./test.sh % echo $? 3

30. Logic: test % test 1 -lt 10 % echo $? 0 % test 1 == 10 % echo $? 1

31. Logic: test test [ ] [ 1 –lt 10 ] [[ ]] [[ “this string” =~ “this” ]] (( )) (( 1 < 10 ))

32. Logic: test [ -f /etc/passwd ] [ ! –f /etc/passwd ] [ -f /etc/passwd –a –f /etc/shadow ] [ -f /etc/passwd –o –f /etc/shadow ]

33. An aside: $(( )) for Math % echo $(( 1 + 2 )) 3 % echo $(( 2 * 3 )) 6 % echo $(( 1 / 3 )) 0

34. Logic: if if something then : # “elif” a contraction of “else if”: elif something-else then : else then : fi

35. Logic: if if [ $USER –eq “borwicjh” ] then : # “elif” a contraction of “else if”: elif ls /etc/oratab then : else then : fi

36. Logic: if # see if a file exists if [ -e /etc/passwd ] then echo “/etc/passwd exists” else echo “/etc/passwd not found!” fi

37. Logic: for for i in 1 2 3 do echo $i done

38. Logic: for for i in /* do echo “Listing $i:” ls -l $i read done

39. Logic: for for i in /* do echo “Listing $i:” ls -l $i read done

40. Logic: for for i in /* do echo “Listing $i:” ls -l $i read done

41. Logic: C-style for for (( expr1 ; expr2 ; expr3 )) do list done

42. Logic: C-style for LIMIT=10 for (( a=1 ; a<=LIMIT ; a++ )) do echo –n “$a ” done

43. Logic: while while something do : done

44. Logic: while a=0; LIMIT=10 while [ &quot;$a&quot; -lt &quot;$LIMIT&quot; ] do echo -n &quot;$a ” a=$(( a + 1 )) done

45. Counters COUNTER=0 while [ -e “$FILE.COUNTER” ] do COUNTER=$(( COUNTER + 1)) done Note: race condition

46. Reusing Code: “Sourcing” % cat > /path/to/my/passwords <<_PW_ FTP_USER=“sct” _PW_ % echo $FTP_USER % . /path/to/my/passwords % echo $FTP_USER sct %

47. 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

48. It takes a long time to become a bash guru…

49. Running Programs

50. Reasons for Running Programs Check Return Code $? Get Job Output OUTPUT=`echo “Hello”` OUTPUT=$(echo “Hello”) Send Output Somewhere Redirection: < , > Pipes

51. 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!

52. Email Notification % echo “Message” | \ mail –s “Here’s your message” \ [email_address]

53. Dates % DATESTRING=`date +%Y%m%d` % echo $DATESTRING 20060125 % man date

54. FTP the Hard Way ftp –n –u server.wfu.edu <<_FTP_ user username password put FILE _FTP_

55. FTP with wget wget \ ftp://user:pass@server.wfu.edu/file wget –r \ ftp://user:pass@server.wfu.edu/dir/

56. FTP with curl curl –T upload-file \ -u username:password \ ftp://server.wfu.edu/dir/file

57. Searching: grep % grep rayra /etc/passwd % grep –r rayra /etc % grep –r RAYRA /etc % grep –ri RAYRA /etc % grep –rli rayra /etc

58. 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

59. Searching: locate % locate .lis [files with .lis in path] % locate log [also finds “/var/log/messages”]

60. Applied Shell Programming

61. Make Your Life Easier TAB completion Control+R history cd - Study a UNIX Editor

62. pushd/popd % cd /tmp % pushd /var/log /var/log /tmp % cd .. % pwd /var % popd /tmp

63. Monitoring processes ps ps –ef ps –u oracle ps –C sshd man ps

64. “DOS” Mode Files #!/usr/bin/bash^M FTP transfer in ASCII, or dos2unix infile > outfile

65. 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_

66. 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! 

67. 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

68. 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

69. 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

70. It's Over!

71. Other Questions? Shells and Shell Scripts bash Running Commands bash and Banner in Practice