File Tests : file test « File « Perl

1. Perl
2. File
3. file test

File Tests

    

#-e True if the file exists.
#-f True if the file is a plain file  not a directory.
#-d True if the file is a directory.
#-z True if the file has zero size.
#-s True if the file has nonzero size  returns size of file in bytes.
#-r True if the file is readable by you.
#-w True if the file is writable by you.
#-x True if the file is executable by you.
#-o True if the file is owned by you.


#!/usr/bin/perl
use warnings;
use strict;
my $target = "myFile";
while (1) {
    if (-e $target) {
        print "File already exists. What should I do?\n";
        print "(Enter 'r' to write to a different name, ";
        print "'o' to overwrite or\n";
        print "'b' to back up to $target.old)\n";
        my $choice = <STDIN>;
        chomp $choice;
        if ($choice eq "r") {
            next;
        } elsif ($choice eq "o") {
            unless (-o $target) {
                print "Can't overwrite $target, it's not yours.\n";
                next;
            }
            unless (-w $target) {
                print "Can't overwrite $target: $!\n";
                next;
            }
        } elsif ($choice eq "b") {
            if ( rename($target,$target.".old") ) {
                print "OK, moved $target to $target.old\n";
            } else {
                print "Couldn't rename file: $!\n";
                next;
            }
        } else {
            print "I didn't understand that answer.\n";
            next;
        }
    }
    last if open OUTPUT, "> $target";
    print "I couldn't write on $target: $!\n";
}
print OUTPUT "Congratulations.\n";
print "Wrote to file $target\n";

   
    
    
    
  

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