Config number of file descriptors on Linux

Check file descriptor limit for a process. Vary depending on owner of the process

$ cat /proc/{process-id}/limits

Check current number of file descriptors of a process

$ sudo ls /proc/{process-id}/fd | wc -l

Set file descriptors limit for a user at /etc/security/limits.conf

*    soft nofile 64000
*    hard nofile 64000
root soft nofile 64000
root hard nofile 64000

Check system file descriptor limit

$ cat /proc/sys/fs/file-max

Check current number of system file descriptors

$ cat /proc/sys/fs/file-nr 

Credits:

• Raising the Maximum Number of File Descriptors (Open Files) on Ubuntu 14.04 Trusty
• https://unix.stackexchange.com/a/104405