You will need root access to increase it. If you're using Ubuntu (also works for other distros): http://ubuntuforums.org/archive/index.php/t-521287.html
If you're using bash, the command is 'ulimit -n'. To change the limit permanently edit /etc/security/limits.conf (your distro may use a different location).
For a list of all options, use -a:
$ ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 20
file size (blocks, -f) unlimited
pending signals (-i) 16382
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 1024
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) unlimited
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited