| Although it is not required, style can make all the difference in how quickly you find bugs in your program. Here are some simple guidelines: -
Put comments in your program so that you and others know what you are trying to do. A cute little trick today may be an time-consuming enigma tomorrow. -
Define variables with meaningful names and put them at the top of the program to help detect spelling errors and null values . Names like foo1 , foo2 , and foo3 really don't say much. Check that you are not using reserved words and pay attention to case sensitivity . -
Whenever you use a conditional or looping command, indent the statement block that follows , at least one tab stop. If conditions or loops are nested, indent further. Align ending keywords with conditional and looping commands such as if and endif , if and fi , while , done , and so on. (See "Missing Keywords" on page 976 and "Indentation" on page 976.) -
Use the echo command in areas where you keep getting a syntax error, or turn on the echoing and verbose switches to trace your program's execution. (See "Tracing with Shell Options and the set Command" on page 1009.) -
Logic errors can be a source for hidden glitches in your program, even if the program runs without error. Know your operators . They vary from shell to shell and are often a cause for a logic error. -
Make your program robust ”check for all possibilities of human error, such as bad input, insufficient arguments, nonexistent files, and the like. (See "Logic Errors and Robustness" on page 1001.) -
Keep things short and simple when testing. For example, if you are using a function, test the syntax , and then try it with a small script to see if you are getting what you want. -
Know your operating system commands . Because most statements consist of UNIX/Linux commands, go to the command line and try the command before using it in a script if you are not sure about how it behaves. Do you understand its exit code , how variables are being interpreted, how to use quotes properly, how to redirect output and errors ? -
Last, if you are a system administrator, test your script carefully before taking it to the system level. An unexpected error could bring a whole system to its knees. The following guidelines will help you with all of these issues and give you a list of the most common syntax errors for each shell, what caused it, and how to fix it. |
