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In the following in Perl script:
$a=apple
$b=orange
if ($?==0) {
# do something
}
What does $? mean here?
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Perl defines a consistent extension syntax for regular expressions. The syntax is a pair of parentheses with a question mark as the first thing within the parentheses (this was a syntax error in older versions of Perl). The character after the question mark gives the function of the extension.
Array Variables The dollar sign ($) is used to refer a single element of an array with the variable name followed by the index of the element in square brackets. Here is an example of how to use an array variable: Perl.
$? is used to find the return value of the last executed command. Try the following in the shell: ls somefile echo $? If somefile exists (regardless whether it is a file or directory), you will get the return value thrown by the ls command, which should be 0 (default "success" return value).
$ is for scalar variables(in your case a string variable.) @ is for arrays.
This is the status returned by the last system operation, pipe, or backtick operation. See reference perlvar.
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