Linux notes

Useful commands¶

cat {print file to screen}
head {see start of file}
tail {see end of file}
dmesg {system errors/logs}
sudo dmesg -c {clear logs}
sudo raspi-config {configure pi}
clear {clear terminal screen}
sudo lsusb -v {list attached USB devices}
ls -l {long list, provides filesize, etc.}
rm -r {recursive remove, works for directories that aren't empty}
stat /tmp/checkpoint {full date info on file}
df {check space remaining on file systems}
which [command]
Increase screen resolution:
sudo nano /home/pi/.vnc/config then add -geometry 1600x900
sudo apt install guake (then F12 to show/hide console, Ctrl-Shift-T for new tab, Ctrl-Page Up/Page Down to navigate) - https://github.com/Guake/guake/
tar -xzf [filename.tar.gz]
less {excellent way to view a file, H for help, Q to quit, lowercase-G jump to start, uppercase-G jump to end}
env to print environment variables
watch to run a command at pre-defined intervals - e.g., watch -n 5 ls to print the directory listing every 5s. Can set to exit when change detected, etc.

to find recursively in folders...
find . -name '*.xml'
ip a (list ip addresses)

Split commands over multiple lines using \ at the end of the line, just ensure no space to the right of it

Handy command list - https://gist.github.com/tuxfight3r/60051ac67c5f0445efee

Terminal colours¶

If terminal reverts to non-coloured then try copying skeleton files back again

Restore skeleton files

cd ~
cp /etc/skel/.profile .profile
cp /etc/skel/.bashrc .bashrc

View logs¶

sudo journalctl -u service-name
last -adF logged in user details sudo lastb -adF failed (bad) logins

Easily view large folders¶

Install duc (http://duc.zevv.nl/) - sudo apt install duc -y
sudo duc index / - to index the entire disk (can change to just a subdirectory, which is quicker) sudo duc ui / - to view in an easily navigable form

Remove large docker elements¶

docker image prune
docker system prune -a
(note will need to recreate the mkdocs-checkforupdates container after that)

Log size¶

Find out how much disk space /var/log/journal is consuming with sudo journalctl --disk-usage

Shrink/Reduce the folder size instantly/immediately (e.g. Delete old log files form /var/log/journal folder, reduce the folder size to 500MB)
sudo journalctl --vacuum-size=500M

Control/Limit the disk space /var/log/journal can use by manually editing the configuration file /etc/systemd/journald.conf
sudo nano /etc/systemd/journald.conf

Uncomment the following line in the configuration file and add the desired sized (e.g., 500MB): SystemMaxUse=500M

tldr¶

Useful alternative to man
Install then run update to cache locally.

sudo apt get install tldr && tldr -u

xdg-open¶

Open current folder in graphical explorer

xdg-open .

Can replace the . with another folder name or a URL.

iperf¶

sudo apt install iperf Run server: iperf -s Connect client: iperf -c <ip_of_server>

Bash tips¶

Ctrl-U clear line
Ctrl-L clear screen
Ctrl-R search command history
cd - to switch between directories

Docker tips¶

Attach to running container docker exec -it [container name] sh

command line startup - either pfetch (v compact) or neofetch (bigger but prettier)¶

wget https://github.com/dylanaraps/pfetch/raw/master/pfetch
chmod +x pfetch
sudo cp pfetch /usr/bin/local

sudo nano ~/.bashrc and add pfetch
sudo nano ~/.config/neofetch/config.conf [to uncomment IP addresses]

btop (formerly bpytop)¶

pre-requisite: sudo apt install bzip2 make
go to https://github.com/aristocratos/btop/releases/latest

wget [latest x64 version for Linode, armv7l for Pi]
tar -xjf [filename].tgz
./install.sh

nano¶

Ctrl-Z to background
fg on terminal to then run again
jobs to list currently running background processes

ncdu¶

shows usage by directory
sudo apt instal ncdu
sudo ncdu -x / (to only show files from root but on local filesystem)

glances¶

pip3 install glances
pip3 install bottle
glances -w
http://192.168.2.138:61208/
can also install as a docker container

if lost bash settings¶

cp /etc/skel/.profile ~/
cp /etc/skel/.bashrc ~/
nano .bashrc and force_color_prompt=yes

Bash history¶

https://www.digitalocean.com/community/tutorials/how-to-use-bash-history-commands-and-expansions-on-a-linux-vps space before command to stop it going into history

export PuTtY settings & sessions¶

regedit /e "%userprofile%\desktop\putty-registry.reg" HKEY_CURRENT_USER\Software\Simontatham

setup SSH keys¶

ssh-keygen -t rsa -b 4096

This creates: id_rsa [private key - to use as identifier on the client when trying to access the host, is in OpenSSH format]
id_rsa.pub [public key - to go into .ssh/authorized_keys file on the host]

cd ~/.ssh
cat id_rsa.pub >> authorized_keys
then move id_rsa to PC

For PuTTY use:
use puttygen (Conversions > Import key > Save private key) to convert this non-.pub file to PuTTY private key format and point to this in Connection > SSH > Auth. Also add username to Connection > Data
https://thepihut.com/blogs/raspberry-pi-tutorials/securely-logging-into-a-raspberry-pi-without-a-password

SSHFS¶

install sshfs and it allows remote directories to be mounted as local directories

upgrading¶

https://www.raspberrypi.org/documentation/raspbian/updating.md
sudo apt dist-upgrade {upgrade to latest version of Raspbian - beware kills wifi}
sudo apt install rpi-update
sudo rpi-update {updates bleeding edge kernel}
uname -r {check kernel version}
https://marcomc.com/2012/09/how-to-fix-regenerate_ssh_host_keys-failed-on-raspbian-for-raspberrypi/ {what to do if SSH fails}

secure SSH access¶

sudo nano /etc/ssh/sshd_config and add PasswordAuthentication no
sudo systemctl restart sshd

Changing desktop https://raspberrypiuser.co.uk/how-to-install-a-new-desktop-environment-using-raspberry-pi-os

Check current path list echo $PATH

Check installed version of a package dpkg-query -l <packagename>

Check available version of a package apt list <packagename>

tmux¶

Good YT video - https://www.youtube.com/watch?v=B-1wGwvUwm8&t=904s reload config - tmux source-file ~/.tmux.config

Hugo¶

hugo server --bind=YOURLINODEPUBLICIP [or replace with FQDN]
-D to allow drafts

Curl¶

Good documentation site re curl: https://everything.curl.dev/