Link Count Of Zero

Met up with some clever guys yesterday and they made me think how Solaris treat deleted files which are still open. We know that if we hard link files in the same file system, it will increment the link count. Do you know that if you delete an open file (with link count of 1), the link count will be become zero (decrement by one). Since the file handler is still open, the kernel will not release those space occupied by the file. So, if you were to do a ls -al, you will see the link count of zero.

To efficiently finding how much space has been taken up by these deleted open files, the below one-liner is able to extract that from find and summaries it by AWK. Here is the output from one of my systems.

# find /proc/*/fd -type f -links 0 -ls | awk '{s+=$7}END{print s}'
159783

This link explained very clearly how the situation come about.