CLI Cheatsheet

Quick Fixes

After a shell finds an executable, it caches its location… except it doesn’t check its own validity. So when you mess with executable locations or the PATH clear that cache with

hash -r # entire cache
hash -d <exe name> # one entry

System Info

uname -a # generic info about the machine
lsb_release -a # what version of my distro am I running?

w # who is logged on and what are they doing
who --all # more information on running users

Apt/Dpkg

List files installed by a package:

dpkg -L some-package

Find out which package installed a given file:

dpkg -S /some/file

Find out what (installed) packages depend on a given package:

apt-cache rdepends  --installed some-package

Install from .deb:

sudo dpkg -i <deb-file>
sudo apt-get install -f

or

sudo apt install <deb-file>

Devices

Find out what device a file or folder is on:

df /path/to/filename

Find out how much storage space is left on drives:

df -H

Run commands when files change

entr is said to have good ergonomics.

This stack overflow answer says to use inotifywait, but mentions some problems, and it’s not installed on my main machine by default. It also mentions fswatch and incron, but again these are not everywhere.

Using mini-httpd in scripts

First off, on some systems it’s mini-httpd, and some its mini_httpd. In any case, if you run it from a script (from a script from a script from a…), then you need a way to shut it down nicely. Otherwise, you need to find it with

ps -ef | grep mini[_-]httpd | awk '{print $2}' | xargs kill
ps -ef | grep [d]efunct | awk '{print $3}' | xargs kill

repeating the second until there are no more defunct processes.

However, you could do the following when starting httpd:

_term() {
  echo "Caught SIGTERM signal!"
  kill "$child" 2>/dev/null
  exit 0
}
trap _term TERM INT HUP QUIT EXIT KILL

port=10080
echo >&3 "Starting server on port $port..."
echo >&3 "(Ctrl-C to exit)"
"$HTTPD" -D -u "$USER" -p "$port" -d <DIR> &
child=$!
wait "$child"

I’m not entirely sure which signals I really have to wait on, but this seems to work. It may even be useful in more general cases.

This was taken from this stack overflow answer. There are more comments and tweaks mentioned there, but it’s worked well enough so far.