W621 - Increasing Productivity with Shell Scripting€¦ · W621 – Increasing Productivity with Shell Scripting Al Freeman Technical Services Cliché statements are generally true

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W621 – Increasing Productivity with Shell Scripting

Al FreemanTechnical Services

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.

Pre-requisites: Unix knowledge

Wednesday, 3:45 p.m.

© 2007 Activant Solutions Inc. All Rights Reserved

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Session Objectives

At the end of this course you will be able toWrite shell scripts to automate proceduresKnow when to and when not to automateKnow where to find more information on commands and their options and arguments



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Return on Investment Opportunity

Avoid unplanned downtimeWork more efficiently, giving more time to

Assist sales and management by implementing high-level tools which turn data into useable informationCreate graphs and reports highlighting opportunities and potential problems Provide longer hours of system availability and increase remote accessibility


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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



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Shell Structures

VariablesPositional parametersCommand substitutionConditional execution


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Shell Structures

VariablesVariables are used to store information during the execution of a shell scriptVariable names should be unique within the first eight charactersBraces { } can be used to delineate the start and end of variable names for clarity

Example:today=${month}${day}${year}



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Shell Structures

Positional parametersAre special variables created by the shellEvery 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 parametersThe "shift" command will move all positional parameters one number lower, discarding the first


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Shell Structures

Command substitutionCommands put in backwards quotes (`) are executed and their output is substituted in place of the commandThis 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”



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Shell Structures

Conditional executiontestifcase

Looping structuresforwhile


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Conditional Execution

The “test” command can be used to determine if a condition is true or notThe “test” command has two formsExamples of two equivalent “test” statements

test "$color" = "white"[ "$color" = "white" ]

“test” is often used with “if” and “while” statements to control execution



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The “if” statement is used to control execution of statements when some condition is metAt 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


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The “if” Statement Structure

if [ "$color" = "white" ]thenwater=hot

elsewater=cold

fi



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The “case” statement is used when execution depends upon multiple values of a single variableAt the end of a “case” statement is an “esac”Value possibilities should be listed from most specific to least specific


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A “case” Statement Example



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Looping Structures

The “for” statement can be used to loop with automatic parameter substitutionThe structure of a for loop isfor variable in list of valuesdo

Statements to be executeddone


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A “for” Statement Example

for file in *.lpdo

lp –dlineptr ${file}done



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Looping Structures

The “while” statement is used to loop while a condition is trueThe structure for a while loop iswhile conditional statement

doStatements to be executed

done


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A “while” Statement Example

# This example will “sleep” until 11:00 PM

now=`date +%H%M` #Gets current timewhile [ "$now" –lt "2300" ]

dosleep 60now=`date +%H%M` #updates now

done



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Automating SDI Programs

There are three types of SDI programsPrograms that have initial inputPrograms that ask questionsFull screen programs


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Programs That Have Initial Input

These are the easiest programs to automateThe format of these programs in a script is

SD-ZIP "PROGRAMNAME~INITIAL_INPUT~~PRINTER"

Most "batch" type programs use this formatA script consisting of these programs can be just SD-ZIP lines one following another or can have more elaborate controls within itMost END-OF-DAY programs are of this type



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Programs That Have Initial Input


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Programs That Ask Questions

A little harder to automate than initial input programs, but still pretty easyThese programs can be automated like this:

SD-ZIP "PROGRAMNAME" <<eofanswer1answer2answer3eofThe eof strings must match or it won't work.



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Programs That Ask Questions


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Full Screen Programs

These are the hardest programs to automateA backup should be run before running any shell script that runs a screen programThere are generally three task categories to running screen programs

Initialization task where you set all the parameters needed for running the programAction task where you actually are doing the work the program is supposed to doFinishing task where you finish up and tell the program to end



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Initialization TaskARCUSTMTN


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Action Task / Exit TaskThis is where the repetitive work will be done

When the repetitive work is done, this is where the program will be ended



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Steps to Writing a Screen Program Script

Figure out what you want to changeManually 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 outIt will be much safer because only the specified fields can then be changed


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Steps to Writing a Screen Program Script

Create a list of the records and values to be changed

Use SDIWriter or Excel with ODBCGet the smallest number of records to change possibleMake sure you get the main key field (Customer #, Part #, etc.) and any fields whose values need to be changedSave as a CSV file for easy processing with a shell



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Write the Main Loop First

This is going to be the most time consuming part of the shellCreate a “for loop” to process every record in the CSV file you created earlierIt’s a good idea to “Home” the cursor on every screen and then tab to the correct field for data entry


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Write the Main Loop First



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Add the Codes to Get to the Main Screen


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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



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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


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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 terminalA typical “expect” script for running SDI in the background#!/usr/local/bin/expect --set timeout -1send "cd /PRISM\r"spawn MY_SPECIAL_SHELL_SCRIPTexpect



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Automating Tasks with “cron”

Use “crontab –e” to edit the crontab fileLogin as root if you want the commands to run as root before using crontab –eLogin as yourself and run “crontab –e” if the programs don’t need to run as rootEach user gets their own “crontab” file which controls the programs that cron will run on that users’ behalf


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The format of the crontab entries isMinute – (0-59) Minute of the hour when the job will runHour – (0-23) Hour of the day when the job will runDay – (1-31) Day of month when the job will runMonth – (1-12) Month of the year when the job will runDay of Week – (0-6) Day of the week on which the job will be run

0=Sunday6=Saturday



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A typical crontab fileEnd of day is being started Monday-Friday at 11:30 PM


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Automating Tasks with “at”

The “at” command can be used to schedule jobs on the fly

Exampleat 8:30 PM todayshutdown –Fr<Ctrl-D>Exampleat now +30 minutesenable printer1<Ctrl-D>



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Additional Resources

Exploring the UNIX System by Stephen G. Kochan and Patrick H. WoodEssential System Administration (Third Edition)by Æleen FrischUNIX “man” command, to get more information about any UNIX command, type “man command” at the $ or # prompt


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Print out the SD-START shell script and try to figure out what each statement doesAdd 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 doAutomate one process using cron

Suggested Action Plan



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Summary

Shell scripts can automate many tasks on the systemEvery SDI program can be run via a shell scriptBackups should be run before running new shell scripts in case the script does something wrongExpect 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


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Thank You for Attending

W621 – Increasing Productivity with Shell ScriptingAl FreemanPlease submit the Session Feedback Form

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W621 - Increasing Productivity with Shell Scripting€¦ · W621 – Increasing Productivity with Shell Scripting Al Freeman Technical Services Cliché statements are generally true