Re: Have a multiple file in directory and want to manipulate in each files in incremental order. All the file have same value.

[GrandFather]

'.' is the current directory and '..' is the parent directory. Neither is a file so you can't open them as a file. You can test for files and skip anything that's not a file:

for my $fileName (@files) {
    next if ! -f $fileName;
    
    open my $in_fh, '<', $fileName;
    ...
}

[graff]

Or, to put that into "plain English" perl:

for my $fileName ( @files ) {
    next unless -f $fileName;
    ...
}