I'm trying to change the file descriptor limits for Apache.

The problem is that the limits set through "/etc/security/limits.conf" don't apply to system users like "apache" with no login shell.

I've tested it with this simple PHP code:

echo "User: ";
echo exec('whoami');
echo "<br>FD Soft Limit: ";
echo exec('ulimit -Sn');
echo "<br>FD Hard Limit: ";
echo exec('ulimit -Hn');

I've also tried to modify a variable from "/usr/sbin/apachectl":

ULIMIT_MAX_FILES="ulimit -S -n `ulimit -H -n`"

OS: CentOS release 6.4 (Final) Apache: Apache/2.2.15


Are you hitting a ceiling of 1,024 file descriptors?

In CentOS/RHEL 6, a new ceiling was introduced by way of /etc/security/limits.d/90-nproc.conf.

This file (and anything in this directory) takes precedence over /etc/security/limits.conf, as it's applied after limits.conf is initially read; and its default is 1,024.

See the history of this via Red Hat Bugzilla, Bug ID #432903.

| improve this answer | |
  • Thanks for reply. Yes, I hit the limit bash: cannot make pipes for command substitution: Too many open files in system. I've tried to change these values in /etc/security/limits.d/90-nproc.conf. however the PHP script still show the defaults (1024/4096)? – HTF Mar 27 '13 at 11:48

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