View current open files for all processes:

lsof -n

Therefore: To list number of files open for all procs:

lsof -n|wc -l

To list for just a particular process:

lsof -p pid

To view the maximum number of files that any single process can open:

ulimit -n

To change the maximum number of files that any single process can open, append the following lines to /etc/security/limits.conf

*                soft    nofile          65535
*                hard    nofile          65535

This will give a hard and soft limit of 65535.

To change the maximum number of files that the entire OS can have open, append the following line to /etc/sysctl.conf

fs.file-max = 100000

Category:Linux