Is there a reason to use IO::File instead of open $fh,'>>',$filename;?

use strict;

sub test {
  my $filename = 'test2.txt';
  if (-f $filename) {
    print "File Exists!";
  } else {
    print "File does not exist";
  }
}

sub openFile {
  open my $fh, '>>', 'test2.txt';
  print "file open!\n";
  print $fh "The stuff I wanted to add to the end of the file.\n";
}

test();
openFile();
test();
[download]

Output:

$: perl foo.pl
File does not exist
file open
File Exists!
$: cat test2.txt
The stuff I wanted to add to the end of the file.
$: perl foo.pl
File Exists!
file open
File Exists!
$: cat test2.txt
The stuff I wanted to add to the end of the file.
The stuff I wanted to add to the end of the file.
$:
[download]

hey thanks for this. there was no reason I was using IO:File apart from what I found online in a tutorial. I found the problem was with where the program was creating the file 'C:\Users\user' instead of that I expected it to create it in the same directory the program is in.

Learning is great. There are tons of modern packages that make this stuff really easy. Path::Tiny, for example, saved me a lot of headache just yesterday in a one-liners renaming a bunch of wget files that had query strings in the file names and couldn't be shared with a Windows user who needed them… I digress. One of many ways to do your task–

Gonna reply to myself while I remember the digression because it was one of those MY LORD, I LOVE PERL moments–

find . -type f | perl -MPath::Tiny -lne '/^(.+?)\?/ && path($_)->move($1)'

Finds names like /this/was-not-a/good.aspx?idea=for&a%20filename and turns them into /this/was-not-a/good.aspx.

$ perl -e 'open my $fh, ">>", "bar.txt" or die "can open file $!"; '
[download]

$ ls -l bar*
-rw-r--r-- 1 Laurent None 0 20 Aug  23:05 bar.txt
[download]

>perl -e "use strict; use warnings;use Fcntl; my $fh; sysopen ($fh, 'f
+ilefilefile.log', O_WRONLY|O_APPEND ) or die $!"
No such file or directory at -e line 1.

>
>
>
>
>
>
>ls filefilefile.log
ls: filefilefile.log: No such file or directory

>
>
>perl -e "use strict; use warnings;use Fcntl; my $fh; sysopen ($fh, 'f
+ilefilefile.log', O_WRONLY|O_EXCL|O_CREAT ) or die
 $!"

>
>
>
>
>ls filefilefile.log
filefilefile.log

>
>
>
------
Here are examples of open and sysopen in action.

To open for reading:

open(FH, "<", $path)                                or die $!;
sysopen(FH, $path, O_RDONLY)                        or die $!;
To open for writing, create a new file if needed, or else truncate an 
+old one:

open(FH, ">", $path)                                or die $!;
sysopen(FH, $path, O_WRONLY|O_TRUNC|O_CREAT)        or die $!;
sysopen(FH, $path, O_WRONLY|O_TRUNC|O_CREAT, 0600)  or die $!;
To open for writing, create a new file, but that file must not previou
+sly exist:

sysopen(FH, $path, O_WRONLY|O_EXCL|O_CREAT)         or die $!;
sysopen(FH, $path, O_WRONLY|O_EXCL|O_CREAT, 0600)   or die $!;
To open for appending, creating it if necessary:

open(FH, ">>", $path)                               or die $!;
sysopen(FH, $path, O_WRONLY|O_APPEND|O_CREAT)       or die $!;
sysopen(FH, $path, O_WRONLY|O_APPEND|O_CREAT, 0600) or die $!;
To open for appending, where the file must exist:

sysopen(FH, $path, O_WRONLY|O_APPEND)               or die $!;
To open for update, where the file must exist:

open(FH, "+<", $path)                               or die $!;
sysopen(FH, $path, O_RDWR)                          or die $!;
To open for update, but create a new file if necessary:

sysopen(FH, $path, O_RDWR|O_CREAT)                  or die $!;
sysopen(FH, $path, O_RDWR|O_CREAT, 0600)            or die $!;
To open for update, where the file must not exist:

sysopen(FH, $path, O_RDWR|O_EXCL|O_CREAT)           or die $!;
sysopen(FH, $path, O_RDWR|O_EXCL|O_CREAT, 0600)     or die $!;
We use a creation mask of 0600 here only to show how to create a priva
+te file. The argument is normally omitted.
[download]

i get bare word error when i complie the script using flags O_RDWR or others, what could be the reason ?

have you imported the module with use Fcntl ? see Fcntl

L*

There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.

I believe that checking to see whether a file exists before creating it can create a race condition. I've been told that the better way to do this is to create the file, and deal with the exception thrown if the file already exists.