Question

I need to check whether a file in a user’s home directory exists so use file check:

if ( -e "~/foo.txt" ) {
   print "yes, it exists!" ;
}

Even though there is a file called foo.txt under the user’s home directory, Perl always
complains that there is no such file or directory. When I replace “~” with /home/jimmy (let’s say the user is jimmy) then Perl give the right verdict.

Could you explain why “~” dosen’t work in Perl and tell me what is Perl’s way to
find a user’s home directory?

Answer 1

~ is a bash-ism rather than a perl-ism, which is why it’s not working. Given that you seem to be on a UNIX-type system, probably the easiest solution is to use the $HOME environment variable, such as:

if ( -e $ENV{"HOME"} . "/foo.txt" ) {
    print "yes ,it exists!" ;
}

And yes, I know the user can change their $HOME environment variable but then I would assume they know what they’re doing. If not, they deserve everything they get 🙂

If you want to do it the right way, you can look into File::HomeDir, which is a lot more platform-savvy. You can see it in action in the following script chkfile.pl:

use File::HomeDir;
$fileSpec = File::HomeDir->my_home . "/foo.txt";
if ( -e $fileSpec ) {
    print "Yes, it exists!\n";
} else {
    print "No, it doesn't!\n";
}

and transcript:

pax$ touch ~/foo.txt ; perl chkfile.pl
Yes, it exists!

pax$ rm -rf ~/foo.txt ; perl chkfile.pl
No, it doesn't!