Re: limit output filesize

I ran this as a test:

#!/usr/bin/perl

use warnings;
use strict;

my $file_base = "output";

open( FILE, ">$file_base" ) or die "Unable to open $file_base for writ
+ing!\n$!\n";

for (1..100) {
  print FILE "0" x 1024;
  print "File Size: ".(stat($file_base))[7]."\n";
  last if (stat($file_base))[7] > 50000;
}


close FILE or die "Error closing $file_base\n$!\n";
[download]

the output was as follows (abridged):

File Size: 0
File Size: 0
File Size: 0
File Size: 0
File Size: 4096
File Size: 4096
File Size: 4096
File Size: 4096
...
File Size: 49152
File Size: 49152
File Size: 49152
File Size: 53248
[download]

So it stopped close to, but not at, 50k because while the file is open, only full blocks are written. You may want to keep that in mind and make sure the cutoff is at the highest blocksize that is less than your threshold.

This is AIX 5.1 on a JFS2 file system. I won't be able to speak for others

Update:
as an aside $|++ did nothing for this
You could also keep tabs on your output size as well, if it is all under your control.

Comment on Re: limit output filesize Select or Download Code

Replies are listed 'Best First'.
Re^2: limit output filesize by rogue90 (Novice) on Jul 08, 2005 at 19:12 UTC
I see - I was using the filehandle for stat. Thanks much!	[reply]
Re^3: limit output filesize by bart (Canon) on Jul 08, 2005 at 19:28 UTC
Urm... the filehandle for stat, actually for `-s`, works for me. `open OUT, ">test.txt"; for (1 .. 1000) { print OUT "Hello, Perlmonks!\n" x 10; print -s OUT; }` [download] It works, but `-s` is indeed set according to the buffer size, and not according to the already printed output: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4096 4096 4096 4096 4096 4096 4096 4096 ... With $\| set to a true value it'll work less coarse, but most likely quite a bit slower: `open OUT, ">test.txt"; my $fh = select OUT; $\| = 1; select $fh; for (1 .. 1000) { print OUT "Hello, Perlmonks!\n" x 10; print -s OUT; }` [download] 192 384 576 768 960 1152 1344 1536 1728 1920 2112 2304 ... I think the coarse version is still fine enough.	[reply] [d/l] [select]
Re^4: limit output filesize by rogue90 (Novice) on Jul 08, 2005 at 19:45 UTC
The coarse version is indeed fine enough. I can limit how frequently I stat which should speed things up a bit. Thanks for your help.	[reply]
Re^4: limit output filesize by rogue90 (Novice) on Jul 08, 2005 at 19:37 UTC
I was just about to say that - if I don't have 1024 chars per line and have say 100 instead it doesn't work the same.	[reply]