General *nix

Run sed on every Rust source file in a directory (GNU):

find . -type f -name '*.rs' -exec sed -i 's/\(DataflowDesc::new(\)None/\1/' {} \;

Above for BSD:

find . -type f -name '*.rs' -exec sed -i '' 's/\(DataflowDesc::new(\)None/\1/' {} \;

Convert a Unix timestamp to a local date/time (GNU):

date -d @1571862547

Above for BSD:

date -r 1571862547

Get number of CPUs (BSD):

sysctl hw.ncpu

Get all the nodes watched in an inotify instance (GNU/Linux):

for f in $(cat fdinfo/6 | perl -ne 'if (/ino:([0-9a-f]*)/) { print hex $1 ; print "\n" }'); do
sudo debugfs -R "ncheck $f" /dev/nvme0n1p1 2>/dev/null | awk 'BEGIN {d=1} {d=!d; if (d) {print $0}}'
done

Arch

Check what package owns a file:

pacman -Qo `which tail`

Checkout the source for a a package:

asp checkout coreutils

Ubuntu

Find files associated with a given package:

dpkg-query -L <package>

FreeBSD server admin

Renew LetsEncrypt certificate:

certbot-3.6 renew
service dovecot onerestart
service nginx onerestart
# And whatever else you might need to restart...

Install patches:

freebsd-update fetch
freebsd-update install

Docker

Blow away a bunch of stuff (caches, unused volumes, etc):

docker system prune -a && docker volume prune

Miscellaneous

Render Graphviz graph:

dot -T pdf < graph.dot > graph.pdf

Render this file:

rst2html < howtodo.rst > howtodo.html