Unix Tipz & Tricz

There is a maximum limit for number of file descriptors in a Linux box.

A file descriptor is a data structure used by a program to get a handle on a file, the most well know being 0,1,2 for standard in, standard out, and standard error. The file-max kernel parameter refers to open file descriptors, and file-nr gives us the current number of open file descriptors.

The below command provides the required details:

# cat /proc/sys/fs/file-nr

3391    969     52427

|       |       |

|       |       |

|        |       maximum open file descriptors

|        total free allocated file descriptors

total allocated file descriptors

(the number of file descriptors allocated since boot)

The maximum open file descriptors parameter is fixed in the file /proc/sys/fs/file-max

To change the number of open file descriptors:

echo "104854" > /proc/sys/fs/file-max