Relative file paths in perl

Question

I have a perl script that uses relative file paths.

Relative paths apparently refer to the location from which the script is being run, and not to the location of the perl script. How to make my relative paths relative to the location of the script?

For example, I have a directory structure

dataFileToRead.txt ->bin myPerlScript.pl ->output 

inside perl script I open the file dataFileToRead.txt using the code my $ rawDataName = "../dataFileToRead.txt"; open INPUT, "<", $ rawDataName;

If I run perl script from bin directory, it works fine

If I run it from the parent directory, it will not be able to open the data file.

Answer 1

FindBin is the classic solution to your problem. If you write

 use FindBin; 

then the $FindBin::Bin scalar is the absolute path to the location of your Perl script. You can chdir there before you open the data file, or simply use it in the path of the file you want to open

 my $rawDataName = "$FindBin::Bin/../dataFileToRead.txt"; open my $in, "<", $rawDataName; 

(By the way, it is always better to use lexical file descriptors on nothing but the very old perl.)

Answer 2

To include a relative path in an absolute, you can use Cwd :

 use Cwd qw(realpath); print "'$0' is '", realpath($0), "'\n"; 

Answer 3

Start by figuring out where the script is .

Then get the directory in which it is located. You can use Path :: Class :: File dir() for this.

Finally, you can use chdir to change the current working directory to the directory just identified.

So, theoretically:

 chdir(Path::Class::File->new(abs_path($0))->dir()); 

Answer 4

Relative paths relate to the current working directory . If you have no control over the working directory, you need to find a more reliable way to spcecify the file path, for example. Use absolute paths, or possibly relative paths, that relate to a specific location in the file system.