crystal reports barcode label printing SHELL SCRIPT DEBUGGING in Font

Printing ECC200 in Font SHELL SCRIPT DEBUGGING

CHAPTER 1 SHELL SCRIPT DEBUGGING
Data Matrix Creator In None
Using Barcode generator for Font Control to generate, create Data Matrix ECC200 image in Font applications.
www.OnBarcode.com
UPC A Maker In None
Using Barcode creator for Font Control to generate, create UPC Symbol image in Font applications.
www.OnBarcode.com
$ ./example echo -n "Can you write device drivers " Can you write device drivers read answer n answer=`echo $answer | tr [a-z] [A-Z]` echo $answer | tr [a-z] [A-Z]if [ $answer = Y ] then echo "Wow, you must be very skilled" else echo "Neither can I; I'm just an example shell script" fi Neither can I; I'm just an example shell script
PDF-417 2d Barcode Creator In None
Using Barcode generator for Font Control to generate, create PDF-417 2d barcode image in Font applications.
www.OnBarcode.com
QR Code Creation In None
Using Barcode creation for Font Control to generate, create QR Code 2d barcode image in Font applications.
www.OnBarcode.com
The verbose (-v) option to the shell is more useful if you simply want to see the running code of the script that you re working with (as opposed to the expanded values of variables) to make sure the code is working as designed with the xtrace (-x) option. Both options can be employed together by using set -xv, and you ll see both types of output at the same time, although it may be difficult to wade through. Both the verbose and xtrace options are valuable in their own way for troubleshooting both logical and syntactical problems. As with all options to the shell, they can be turned on and off. The syntax for disabling an option is the opposite of that for turning on an option. Instead of using a minus (-) sign as you did before to enable an option such as in -x, you would use a plus sign, as in +x to disable the option. This will disable the option from that point on. This is very useful if you want to debug only a small portion of the script. You would enable the option just prior to the problem area of code, and disable it just after the problem area so you aren t inundated with irrelevant output.
European Article Number 13 Maker In None
Using Barcode drawer for Font Control to generate, create EAN-13 Supplement 5 image in Font applications.
www.OnBarcode.com
Painting Code 128 In None
Using Barcode printer for Font Control to generate, create Code 128 Code Set B image in Font applications.
www.OnBarcode.com
Simple Output Statements
Create Code 39 In None
Using Barcode printer for Font Control to generate, create Code-39 image in Font applications.
www.OnBarcode.com
NW-7 Creation In None
Using Barcode generation for Font Control to generate, create Rationalized Codabar image in Font applications.
www.OnBarcode.com
The next debugging technique the use of echo or print commands in the code is also very simple, but it is used frequently to gather specific variable values from a running script rather than displaying potentially large amounts of data using the set -x option. Typically these commands are used for simple output of a script to some type of display or file. In this case, however, they will be used as a checkpoint in the code to validate variable assignments. These additional output instructions are used regularly in at least a couple of ways. The first way is to output the value of a specific variable at a specific time. Sometimes variables get changed when you aren t expecting them to be, and adding a simple output line will show this. The main advantage of this type of output compared to set -x is that you have the ability to format your output for ease of reading. While set -x has a valid use and is
Data Matrix 2d Barcode Recognizer In .NET Framework
Using Barcode scanner for .NET Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
Data Matrix Encoder In Java
Using Barcode encoder for Java Control to generate, create ECC200 image in Java applications.
www.OnBarcode.com
CHAPTER 1 SHELL SCRIPT DEBUGGING
Reading Code 128B In .NET Framework
Using Barcode decoder for Visual Studio .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
PDF 417 Recognizer In VS .NET
Using Barcode scanner for .NET framework Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
valuable in tracing through the running of a script, it can be cumbersome to isolate the exact piece of data that you re looking for. With an echo or print statement, you can display a single line of output with multiple variables that include some headings for easy reading. The following line is an example of the code you might use:
Printing GTIN - 13 In C#.NET
Using Barcode drawer for VS .NET Control to generate, create GS1 - 13 image in VS .NET applications.
www.OnBarcode.com
Encode EAN / UCC - 13 In Objective-C
Using Barcode printer for iPhone Control to generate, create EAN-13 Supplement 5 image in iPhone applications.
www.OnBarcode.com
echo Var1: $var1 Var2: $var2 Var3: $var3
Generating Denso QR Bar Code In Java
Using Barcode drawer for Java Control to generate, create QR image in Java applications.
www.OnBarcode.com
Barcode Maker In .NET
Using Barcode encoder for .NET Control to generate, create Barcode image in Visual Studio .NET applications.
www.OnBarcode.com
The output doesn t need to be polished since it is simply for your validation and troubleshooting, but you will want it to be meaningful so you can see the exact data you re looking for at its exact spot in the code. The second way is to output a debugging line to verify that the logic is correct for known input data. If you are running a script that should have known results but does not, it may contain a logical error where what you ve designed and what you ve coded don t quite match. Such errors can be difficult to find. Adding some echo statements in key positions can reveal the flow of control through the script as it executes, and so validate whether you are performing the correct logical steps. I ve modified the script slightly to add echo statements at two key positions, but only one of the statements in each echo-statement pair will be executed because of the if statement. This way you not only see the output of the statement itself, but you know which condition of the if statement the code executed. In the following very simple example code, you can see that there is an echo statement as part of the original code. When there are many conditions and comparisons without output, these types of statements are very valuable in determining if your logic is correct.
QR Code Encoder In Java
Using Barcode encoder for Android Control to generate, create QR Code image in Android applications.
www.OnBarcode.com
UPC Symbol Creation In Java
Using Barcode generation for Java Control to generate, create UPCA image in Java applications.
www.OnBarcode.com
#!/bin/sh echo -n "Can you write device drivers " read answer answer=`echo $answer | tr [a-z] [A-Z]` if [ $answer = Y ] then echo Wow, you must be very skilled echo this is answer: $answer else echo Neither can I, Im just an example shell script echo this is answer: $answer fi
Read UPC Symbol In Java
Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
Painting GTIN - 128 In Objective-C
Using Barcode printer for iPhone Control to generate, create EAN / UCC - 14 image in iPhone applications.
www.OnBarcode.com
Tip I tend not to format these debugging echo statements with the traditional indentation because they
are usually temporary additions while I m troubleshooting. Indenting them with the normal code makes them more difficult to find when I want them removed.
Copyright © OnBarcode.com . All rights reserved.