On Sun, Apr 25, 2010 at 05:02:05PM -0700, wenlong wrote: > Hi All, > > Today, I'm playing with the "ulimit " command. My login has a ulimit > of 1024 for open file descriptor: > > $ ulimit -n > 1204 > > But when using lsof to list down all files (files, socket, etc) opened > by my login, I got: > > $ lsof -u user | wc -l > 3977 > > Can someone tell me why can my login open more files than granted by > ulimit? I'm running: > > Debian stable (lenny) > Gnome desktop environment + compiz > > Thanks. > > -- wenlong (boon leong) > > -- > You received this message because you are subscribed to the Linux Users Group. > To post a message, send email to [email protected] > To unsubscribe, send email to [email protected] > For more options, visit our group at > http://groups.google.com/group/linuxusersgroup
The ulimit -n is a per-process limitation (i.e. any process cannot have more
than 1024 files open). Here is a brief example, showing a process that can
open 1024 files, but not 1025 (bearing in mind that there are already 3 files
open: stdin, stdout, and stderr):
egg...@pokeserver ~ $ ulimit -n
1024
egg...@pokeserver ~ $ lsof | grep eggled | wc -l
4863
egg...@pokeserver ~ $ cat openLots.pl
#!/usr/bin/perl
## There are already 3 file descriptors
## Plus an offset to make the index equal to the file count.
my @fileList = (-1,0,1,2);
for (;;) {
push(@fileList,">/tmp/lotsaFilesTemp.$#fileList");
open($fileList[$#fileList],$fileList[$#fileList]) or (print "\n\n" and
die "\n\nCould not open $#fileList: $!");
print "$#fileList ";
}
egg...@pokeserver ~ $ ./openLots.pl
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
---- snip ----
1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021
1022 1023 1024
Could not open 1025: Too many open files at ./openLots.pl line 8.
egg...@pokeserver ~ $
The 1025th file failed to open, with the error message "Too many files open".
pgp3Mg16r88G2.pgp
Description: PGP signature
