Linux in General

Determining the full path of a command

which command

Determine what the command is

type command

Create a user

useradd --create-home tomk

# if there are any ssh keys to attach to the user
# paste them in seperate lines in .ssh/authorized_keys (under user home dir)

Add an existing user to an existing group

usermod -a -G group_name user_name

Determining the package that installed a specific file (Debian)

dpkg -S /path/to/file
#or, directly on a command like so
dpkg -S `which command`

List files installed by a specific package (Debian)

dpkg-query -L <package-name>

List files a .deb file will install (Debian)

dpkg-deb -c <package-name.deb>

chmod numbers representation:

--x
-w-
-wx
r--
r-x
rw-
rwx

Show all the sudo permissions of a user

sudo -l

Using less with color:

jq -C . data.json | less -R