W621 Increasing Productivity with Shell Scripting

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1 W621 Increasing Productivity with Shell Scripting Pre-requisites: Unix knowledge Cliché statements are generally true. Isn t it better to work smarter not harder? While many companies opt to pay for custom software or continue to manually handle repetitive tasks, those a bit savvier utilize UNIX scripts to automate procedures. This session will cover more advanced shell scripting techniques specifically for SDI users, such as running any SDI program from a shell script, including interactive forms programs; customizing your END-OF-DAY for different days of the week or month with conditional execution; and using "expect" and "cron" to automate nearly anything on the system. Al Freeman Technical Services Wednesday, 3:45 p.m. 2 Session Objectives At the end of this course you will be able to Write shell scripts to automate procedures Know when to and when not to automate Know where to find more information on commands and their options and arguments

2 3 Return on Investment Opportunity Avoid unplanned downtime Work more efficiently, giving more time to Assist sales and management by implementing highlevel tools which turn data into useable information Create graphs and reports highlighting opportunities and potential problems Provide longer hours of system availability and increase remote accessibility 4 Case Study Activant SDI customer, APCO, Inc., wrote a shell script to import price updates into their SDI system saving them hours of manual labor each month They saved additionally by not having a custom program written to do these updates

3 5 Shell Structures Variables Positional parameters Command substitution Conditional execution 6 Shell Structures Variables Variables are used to store information during the execution of a shell script Variable names should be unique within the first eight characters Braces { } can be used to delineate the start and end of variable names for clarity Example: today=${month}${day}${year}

4 7 Shell Structures Positional parameters Are special variables created by the shell Every word on the command line is assigned a number, the first word is 0, the second is 1, etc. Use $# to get the value of the parameter $0 is the first word (the command), $1 is the first argument to the command, etc Use $* to get the values of all parameters The "shift" command will move all positional parameters one number lower, discarding the first 8 Shell Structures Command substitution Commands put in backwards quotes (`) are executed and their output is substituted in place of the command This is often used to get information into variables in shell scripts Example: today=`date +%m%d%y` puts the current date in MMDDYY format into the variable called today

5 9 Shell Structures Conditional execution test if case Looping structures for while 10 Conditional Execution The test command can be used to determine if a condition is true or not The test command has two forms Examples of two equivalent test statements test "$color" = "white" [ "$color" = "white" ] test is often used with if and while statements to control execution

6 11 Conditional Execution The if statement is used to control execution of statements when some condition is met At the end of an if statement is a fi else and elif are allowed to control what happens when the condition for the if is not true 12 The if Statement Structure if [ "$color" = "white" ] then water=hot else water=cold fi

7 13 Conditional Execution The case statement is used when execution depends upon multiple values of a single variable At the end of a case statement is an esac Value possibilities should be listed from most specific to least specific 14 A case Statement Example

8 15 Looping Structures The for statement can be used to loop with automatic parameter substitution The structure of a for loop is for variable in list of values do Statements to be executed done 16 A for Statement Example for file in *.lp do lp dlineptr ${file} done

9 17 Looping Structures The while statement is used to loop while a condition is true The structure for a while loop is while conditional statement do Statements to be executed done 18 A while Statement Example # This example will sleep until 11:00 PM now=`date +%H%M` #Gets current time while [ "$now" lt "2300" ] do sleep 60 now=`date +%H%M` #updates now done

10 19 Automating SDI Programs There are three types of SDI programs Programs that have initial input Programs that ask questions Full screen programs 20 Programs That Have Initial Input These are the easiest programs to automate The format of these programs in a script is SD-ZIP "PROGRAMNAME~INITIAL_INPUT~~PRINTER" Most "batch" type programs use this format A script consisting of these programs can be just SD-ZIP lines one following another or can have more elaborate controls within it Most END-OF-DAY programs are of this type

11 21 Programs That Have Initial Input 22 Programs That Ask Questions A little harder to automate than initial input programs, but still pretty easy These programs can be automated like this: SD-ZIP "PROGRAMNAME" <<eof answer1 answer2 answer3 eof The eof strings must match or it won't work.

12 23 Programs That Ask Questions 24 Full Screen Programs These are the hardest programs to automate A backup should be run before running any shell script that runs a screen program There are generally three task categories to running screen programs Initialization task where you set all the parameters needed for running the program Action task where you actually are doing the work the program is supposed to do Finishing task where you finish up and tell the program to end

13 25 Initialization Task ARCUSTMTN 26 Action Task / Exit Task This is where the repetitive work will be done When the repetitive work is done, this is where the program will be ended

14 27 Steps to Writing a Screen Program Script Figure out what you want to change Manually go through the process of changing two records and record every key that you hit If the program has a way to reduce the number of fields which can be changed like ARCUSTMTN or INMAINT, make sure the fewest possible fields can be changed It will make writing the script easier because there will be fewer keystrokes to figure out It will be much safer because only the specified fields can then be changed 28 Steps to Writing a Screen Program Script Create a list of the records and values to be changed Use SDIWriter or Excel with ODBC Get the smallest number of records to change possible Make sure you get the main key field (Customer #, Part #, etc.) and any fields whose values need to be changed Save as a CSV file for easy processing with a shell

15 29 Write the Main Loop First This is going to be the most time consuming part of the shell Create a for loop to process every record in the CSV file you created earlier It s a good idea to Home the cursor on every screen and then tab to the correct field for data entry 30 Write the Main Loop First

16 31 Add the Codes to Get to the Main Screen 32 Add the Codes to End the Program Now the logic of the shell script is complete Running the shell will produce a file called keystrokes which can then be used to run ARCUSTMTN

17 33 Running the Screen Program Once the keystroke file is created it can be used as input to the screen program SD-START ARCUSTMTN <keystrokes Before running the script: make sure you back up every file affected by the program you re going to run from the script 34 Using expect to Run Programs You will need to have expect installed on your system Expect can be used to run programs in the background or through cron that normally require to be run from a terminal A typical expect script for running SDI in the background #!/usr/local/bin/expect -- set timeout -1 send "cd /PRISM\r" spawn MY_SPECIAL_SHELL_SCRIPT expect

18 35 Automating Tasks with cron Use crontab e to edit the crontab file Login as root if you want the commands to run as root before using crontab e Login as yourself and run crontab e if the programs don t need to run as root Each user gets their own crontab file which controls the programs that cron will run on that users behalf 36 Automating Tasks with cron The format of the crontab entries is Minute (0-59) Minute of the hour when the job will run Hour (0-23) Hour of the day when the job will run Day (1-31) Day of month when the job will run Month (1-12) Month of the year when the job will run Day of Week (0-6) Day of the week on which the job will be run 0=Sunday 6=Saturday

19 37 Automating Tasks with cron A typical crontab file End of day is being started Monday-Friday at 11:30 PM 38 Automating Tasks with at The at command can be used to schedule jobs on the fly Example at 8:30 PM today shutdown Fr <Ctrl-D> Example at now +30 minutes enable printer1 <Ctrl-D>

20 39 Additional Resources Exploring the UNIX System by Stephen G. Kochan and Patrick H. Wood Essential System Administration (Third Edition) by Æleen Frisch UNIX man command, to get more information about any UNIX command, type man command at the $ or # prompt 40 Suggested Action Plan Print out the SD-START shell script and try to figure out what each statement does Add at least one program to your END-OF-DAY process on your own. Write at least one shell script to do something that you frequently are required to do Automate one process using cron

21 41 Summary Shell scripts can automate many tasks on the system Every SDI program can be run via a shell script Backups should be run before running new shell scripts in case the script does something wrong Expect can be used to run programs that require terminals in the background (or through cron) Cron can automatically execute programs at specific times and days 42 Thank You for Attending W621 Increasing Productivity with Shell Scripting Al Freeman Please submit the Session Feedback Form To receive NASBA credits, please be sure to complete the Session Feedback Form and sign the class roster in the back of the room

23 Session Feedback Form Summit 2007 Las Vegas, NV Please take a moment to evaluate this session and offer feedback. Activant uses your input to understand your needs and to determine future Summit sessions. Session Name: Session Number: Presenter s Name: How important is this topic to your job/company? Not Important Important Please rate the educational value you received from this session Low Value High Value 1. What software are you currently using? 2. How long have you personally used this software? 3. Describe the effectiveness of your instructor. 4. What is your overall evaluation of this session? 5. What could have been done to improve this session? 6. What sessions would you like to see presented at future conferences? 7. What issues will be critical to your business in the next months? Check here if you would like CPE credits. To receive credits, be sure to sign your name at the bottom of this form and sign the roster in the session room. Answering the following questions is OPTIONAL (but required for CPE Credits). Yes No Did this session meet your expectations, based on the description/objectives in the registration materials? Were the pre-requisite requirements stated in the course description appropriate? Did the session materials contribute to achieving the learning objectives? Did the equipment (screen, microphone, projector, etc.) in the room enhance the instruction? Was the time allotted for the session appropriate for the topic? Name: Company:

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