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

Print a number with digit separator:

LC_NUMERIC=en_US.utf8 printf "%'.f\n" # On FreeBSD: LC_NUMERIC=en_US.UTF-8

Find what process is listening on a port (Linux):

sudo lsof -i :8080

Find executable files under current directory (GNU):

find . -type f -executable

Above for FreeBSD:

find . -type f -perm -u+x

Diff the output of two commands (bash/zsh):

diff <(ls) <(ls -a)

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>

Check what package owns a file:

dpkg -S /bin/ls

Get source code for a package:

apt-get source xscreensaver

FreeBSD

Get reverse dependencies of a package:

pkg info -r wayland

Print a package's install message:

pkg query %M sshguard

OpenBSD

Search for a package:

pkg_info -Q gtk

Get installed reverse dependencies of a package:

pkg_info -R rust

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

Kill all running containers:

docker ps|tail -n +2|awk '{print $1}'|xargs docker kill

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

docker system prune -a && docker volume prune

Rust

Patch a dependency from crates.io:

[patch.crates-io]
bar = { path = "/path/to/bar" }

Patch a dependency from GitHub:

# Note that the crate name (here `timely`) might differ from
# the repo name (here `timely-dataflow`).

[patch."https://github.com/TimelyDataflow/timely-dataflow"]
timely = { path = "/path/to/timely" }

Git

Delete a remote branch:

git push <remote> --delete <branch>

Check whether a commit is on a given branch:

git merge-base --is-ancestor <commit> <branch> && echo "it's there" || echo "nope"

Print the root directory of the repository:

git rev-parse --show-toplevel

Change the commit hash (e.g., to kick off a new CI run):

git commit --amend --no-edit

Default Ports

Service	Port
Confluent Schema Registry	8081
Zookeeper	2181
Kafka	9092
SMTP	25
SMTPS	465
SMTP submission	587
IMAP	143
IMAPS	993
Confluent Control Center	9021
Grafana	3000
Hugo	1313
SQL Server	1433
Kafka Connect	8083
PostgreSQL	5432
Materialize	6875
OpenVPN	1194 (UDP)

Vim

Find out why startup is slow:

vim --startuptime out_file

Reload .vimrc:

:so $MYVIMRC

Trick to write a file as root:

:w !sudo tee %

Confluent

Start with a different data directory:

CONFLUENT_CURRENT=/some/where confluent local start

Miscellaneous

Render Graphviz graph:

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

Render this file:

rst2html < howtodo.rst > howtodo.html

Detach all other tmux clients:

tmux detach-client -a

OpenSSL equivalent of netcat:

openssl s_client -quiet -connect example.com:443