Learning Perl on Win32 Systems

Chapter 12. Directory Access

Moving Around the Directory Tree

By now, you’re probably familiar with the notion of the current directory and using the cd command at the command prompt. If you were programming in C, you’d be invoking the chdir () call to change the current directory of a program; this name is also used by Perl.

The chdir function in Perl takes a single argument—an expression evaluating to a directory name to which the current directory will be set. As with most other system calls, chdir returns true if you’ve successfully changed to the requested directory and false if you couldn’t. Here’s an example:

chdir("c:/temp") || die "cannot cd to c:/temp ($!)";

The parentheses are optional, so you can also get away with stuff like:

print "where do you want to go? ";
chomp($where = <STDIN>);
if (chdir $where) {
		# we got there
} else {
		# we didn'
t get there

}

You can’t find out where you are without launching a cc command (something like cmd /c cd, or some moral equivalent^[78]). We’ll learn about launching commands in Chapter 14.

Every process^[79] has its own current directory. When a new process is launched, it inherits its parent’s current directory, but that’s the end of the connection. If your Perl program changes its directory, the change won’t affect the parent program that launched the Perl process. Likewise, the processes that the Perl program creates cannot affect that Perl program’s current directory. The current directories for these new processes are inherited from ...