Update cheatsheets

tldr/linux/lsfd

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+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# lsfd
+
+> List open files and the corresponding processes in Linux.
+> More information: <https://manned.org/lsfd>.
+
+- List all open file descriptors:
+
+`lsfd`
+
+- List all files kept open by a specific program:
+
+`lsfd -Q 'PID == {{process_ID}}'`
+
+- Check what program has a specific file open:
+
+`lsfd -Q "NAME == '{{/path/to/file}}'"`
+
+- List open IPv4 or IPv6 sockets:
+
+`lsfd -i{{4|6}}`