====== lsof ======
===== Description =====
list open files

===== Example: Which ports are open? =====
  * Updated, better example<code>
lsof -i TCP
</code>
  * Older example<code>
# lsof | grep TCP
portmap    2587   rpc    4u     IPv4       5544                 TCP *:sunrpc (LISTEN)
rpc.statd  2606  root    6u     IPv4       5585                 TCP *:668 (LISTEN)
sshd       2788  root    3u     IPv6       5991                 TCP *:ssh (LISTEN)
sendmail   2843  root    4u     IPv4       6160                 TCP badhd:smtp (LISTEN)
vsftpd     9337  root    3u     IPv4      34949                 TCP *:ftp (LISTEN)
cupsd     16459  root    0u     IPv4      41061                 TCP badhd:ipp (LISTEN)
sshd      16892  root    3u     IPv6      61003                 TCP badhd.mshome.net:ssh->kontiki.mshome.net:4661 (ESTABLISHED)
</code>

===== Example: Show files open by Quicktime =====
<code>lsof -c QuickTime</code>

===== Example: Show files open by a user =====
  * you can replace sort | uniq with "sort -u"
<code>
lsof | grep ' root ' | awk '{print $NF}' | sort | uniq | wc -l
179
</code>