Wednesday, March 11, 2020

How to Tell if a File Exists in Perl

How to Tell if a File Exists in Perl Perl has a set of useful file test operators that can be used to  see whether a file exists or not. Among them is -e, which checks to see if a file exists. This information could be useful to you when you are working on a script that needs access to a specific file, and you want to be sure that the file is there before performing operations. If, for example, your script has a log or a configuration file that it depends upon, check for it first. The example script below throws a descriptive error if a file is not found using this test. #!/usr/bin/perl$filename /path/to/your/file.doc;if (-e $filename) {print File Exists!;} First, you create a string that contains the path to the file that you want to test. Then you wrap the -e (exists) statement in a conditional block so that the print statement (or whatever you put there) is only called if the file exists. You could test for the opposite- that the file does not exist- by using the unless conditional: unless (-e $filename) {print File Doesnt Exist!;} Other File Test Operators You can test for two or more things at a time using the and () or the or (||) operators. Some other Perl file test operators are: -r checks if the file is readable-w checks if the file is writeable-x checks if the file is executable-z checks if the file is empty-f checks if the file is a plain file-d checks if the file is a directory-l checks if the file is a symbolic link Using a file test can help you avoid errors or make you aware of an error that needs to be fixed.