Hi guys,

I recently came across a weird error. It happened a few times. Seems very random, but usually tend to happen around a specific time. Below is the code:

my $file_name = 'abc.txt';

# abc.txt is just one line simple txt file like "Hello world!". It's c
+reated by another program. The second the other program creates it, t
+he code below tries to read it.

# I know the following code is not the right thing to do. I would do i
+t open (my $FILE, '<', $file_name) for reading. But it's legacy code 
+and how the error is produced. So I just show it the way it is now.

open(FILE, $file_name) or die "Can't open file $file_name $!\n");
my $line = <FILE>;
print $line;
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The random error is, it's able to open the file (the die action never happens), but unable to read any data ($line is uninitialized)

If I rerun it after a couple minutes, it runs fine and $line does get the data

My best guess is that the bug is due to legacy "open(FILE, $file_name)" code. Because it did not specify "<" read mode, after it opens the file successfully, another program somehow gets able to write it. Then this program was not able to read it. Is that a fair guess? Anybody has better idea how to fix it? Thanks!