Re: Determine whether file is dos or unix format

This simple piece of code should do the trick for you...

open FILE, 'test_file.txt' || die "$!\n";
my $text = join( '', @{ [ <FILE> ] } );
close FILE;

die "The file supplied is not of unix format!\n" if ( $text =~ /\r\n/ 
+);
[download]

You might not want to take this snippet as literal, for it will load the entire contents of the file into memory and test the entite thing. This will be quite inneficient. However, this should give you the general idea of how to do what you are looking for.

Update:
I might as well give you an example of something that will be, possibly, a little less memory intensive:

open FILE, 'test_file.txt' || die "$!\n";
while ( my $line = <FILE> ) {
  die "File is not of UNIX format!\n" if ( $line =~ /\r\n/ );
  last;
}
close FILE;
[download]

This one will only check the first line for Windows format. If it finds it, it will die; otherwise will simply move on with the rest of the application.

Good Luck!

---hA||ta----
print map{$_.' '}grep{/\w+/}@{[reverse(qw{Perl Code})]} or die while ( 'trying' );

Comment on Re: Determine whether file is dos or unix format Select or Download Code

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Re^2: Determine whether file is dos or unix format by ikegami (Patriarch) on Nov 28, 2005 at 21:52 UTC
The snippet `open FILE, 'test_file.txt' \|\| die "$!\n"; my $text = join( '', @{ [ <FILE> ] } ); close FILE;` [download] will never `die` on error, is inefficient, uses a global variable (`FILE`), would be safer if the 3 parameter `open` was used, and will not work on a Windows (and other?) machines without `binmode`. It will never `die` because "`\|\|`" has higher precedence than "`,`". `open FILE, 'test_file.txt' \|\| die "$!\n";` means `open FILE, ('test_file.txt' \|\| die "$!\n");` so use `open FILE, 'test_file.txt' or die "$!\n";` or `open(FILE, 'test_file.txt') \|\| die "$!\n";` It is ineffecient you create an anonymous array and immediately dereference it. `join( '', @{ [ <FILE> ] } );` is equivalent to `join( '', <FILE> );` It is also ineffecient because `join` is slower and less memory efficient than undefining `$/`. `my $text = join( '', <FILE> );` is equivalent to the more efficient `my $text; { local $/; $text = <FILE>; }` So you end up with `my $text; { open(my $fh, '<', 'test_file.txt') or die("Unable to open input file: $!\n"); binmode($fh); local $/; $text = <$fh>; }` [download]	[reply] [d/l] [select]
Re^3: Determine whether file is dos or unix format by blazar (Canon) on Nov 29, 2005 at 08:16 UTC
I second of all of what you wrote in this detailed and precise post. Only I feel like adding for completeness that re binmode, an alternative is given by layers/disciplines, and an IMHO clear one in terms of readability intelligibility. And I'm keen on do too, so all in all I'd rewrite the above like `my $text = do { open my $fh, '<:raw', 'test_file.txt' or die "Unable to open input file: $!\n"; local $/; <$fh>; };` [download]	[reply] [d/l]
Re^4: Determine whether file is dos or unix format by ikegami (Patriarch) on Nov 29, 2005 at 16:16 UTC
`my $text = do { ... };` is slower than `my $text; { $text = ...; }` and requires twice as much memory. I agree that it looks nicer, and I usually use it for that reason.	[reply] [d/l] [select]