Useful Linux Examples
Eclectic collection of useful things in Linux
Run last command again with sudo
sudo !!
In the fish shell: Alt + s will prefix a command with sudo, so pair that with up-arrow to go back to last command
Working with Processes
Run my command in the background and intercept SIGHUP’s sent to the command
nohup my_command &
Let me exit this shell that owns the process identified by pid without sending SIGHUP to it
disown <pid>
Find existing process’s id
ps -ef | grep <substing of command>
Kill all the things (with a filter)
kill -9 `ps -aef | grep <substing of command> | awk '{print $2}'`
Environment variables
Set environment variables from .env file
export $(grep -v '^#' .env | xargs -d '\n')
Fish
set -x ENV_VAR_NAME ENV_VAR_VALUE
Automation
Makefile’s are good for easily running developer environment setup, builds,
and other repeatable tasks for a code base / repository. Additionally, it serves a great
duel use as documentation on how to work with the project
SHELL := /bin/bash # Use bash syntax, by default uses /bin/sh
EXAMPLE ?= default # $EXAMPLE env var value if set else default
MAKEFILE_PATH := $(abspath $(lastword $(MAKEFILE_LIST)))
MAKEFILE_DIR := $(patsubst %/,%,$(dir $(MAKEFILE_PATH)))
.ONESHELL: # commands inside the same target run inside the same shell
.PHONY: thing1
thing1:
echo "Thing 1"
.PHONY: thing2
thing2: thing1 # thing2 depends on thing1
echo "Thing 2"
echo "$(shell pwd)" # how to nest shell commands
Usage: make thing2
Bash to Fish conversion
Bash
$(...)
Fish
(...)
Git
How many commits do I need to rebase?
git rev-list --count HEAD ^origin/master
# if you merge other branches into yours, this will filter out the extra branches
git rev-list --count --first-parent HEAD ^origin/master
If you need to exclude merges you can use the --no-merges flag too
Useful packages
- yadm - Yet Another Dotfile Manager, very useful for managing config settings of other applications, e.g. mine are here
- fish - Better shell than bash, nice autocompletion
- Starship - Terminal prompt useful for understanding context you are in
- Alacritty - Good terminal emulator
tmux- Terminal Multiplexer- pyenv - Manage Python Environments
- ripgrep -
rgbetter grep
SSH
Add aliases for servers you connect to
.ssh/config
Host <alias>
HostName <IP address / DNS>
User <username>
ssh-copy-id - Copy ssh key to server, to avoid needing to type in password
Use your host’s SSH keys within a docker container
Dockerfile
docker run \
--env SSH_AUTH_SOCK=/ssh-agent \
--volume $SSH_AUTH_SOCK:/ssh-agent \
...
or equivalent docker-compose.yml
my-service:
...
volumes:
- $SSH_AUTH_SOCK:/ssh-agent
environment:
SSH_AUTH_SOCK=/ssh-agent