// Computer Tips

I frequently find myself needing to lookup how to do simple things with Linux and programming all the time. This page serves as a continuously updated repository of useful commands which I need to use frequently:

General

Grab all files of a given type from a webpage

wget -r -np -nd -l 0 -A.pdf http://security.cs.rpi.edu/courses/binexp-spring2015/lectures/

Adjust External Monitor Brightness

xrandr --output HDMI-1 --brightness 0.5

Edit all images in-place

# wxh+left+top
# Cropping
mogrify -crop 640x330+0+0 *.jpg
# Resizing
mogrify -resize 640x330+0+0 *.jpg

Photo Metadata

# Read metadata
exiftool /tmp/my_photo.jpg
# Delete metadata
exiftool -overwrite_original_in_place -all= /tmp/my_photo.jpg

Create a softlink

ln -s <src> <dest>

Change Git Remote URL for Forks

git remote set-url origin https://github.com/USERNAME/REPOSITORY.git

Get all Git submodules

git submodule update --init --recursive

Change Video Bitrate

# To get a 4mbps video
ffmpeg -i input.mp4 -b 4000k output.mp4

Make LaTeX Machine Readable

% Add these two lines in your preamble
\input{glyphtounicode}
\pdfgentounicode=1

Get Windows BIOS Keys

sudo hexdump -s 56 -e \'"MSDM key: " /29 "%s\n"\' /sys/firmware/acpi/tables/MSDM

Watch a Directory

# Updates every 0.1s
watch -n 0.1 ls -lt .

Fix Ubuntu and Windows Time Sync issues

timedatectl set-local-rtc 1 --adjust-system-clock

SSHFS Example

sshfs USER@IP:/$PATH $LOCAL_PATH

Copy SSH keys to server

ssh-copy-id id@server

Screen Tips

# Create a named screen
screen -S myscreen
# Reconnect
screen -r myscreen
# List screens
screen -ls
# Detach
Ctrl+A+D

Jekyll Setup

sudo apt-get install ruby-full build-essential zlib1g-dev
gem install jekyll bundler
bundle install
bundle exec jekyll serve --watch --trace
bundler exec jekyll build && bash -c \'cd _site && python -m http.server 3000\' # workaround for Ruby3

Boot Repair Setup

sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install -y boot-repair && boot-repair

Fix annoying K380 function key defaults

# Download and build configuration script from https://github.com/jergusg/k380-function-keys-conf
# Then add the below to the root\'s crontab: * * * * * /home/nic/k380hack.sh
# k380hack.sh
/home/nic/software/k380-function-keys-conf/k380_conf -d /dev/hidraw0 -f on
/home/nic/software/k380-function-keys-conf/k380_conf -d /dev/hidraw1 -f on
/home/nic/software/k380-function-keys-conf/k380_conf -d /dev/hidraw2 -f on
/home/nic/software/k380-function-keys-conf/k380_conf -d /dev/hidraw3 -f on
/home/nic/software/k380-function-keys-conf/k380_conf -d /dev/hidraw4 -f on
/home/nic/software/k380-function-keys-conf/k380_conf -d /dev/hidraw5 -f on
# Clean? No. Effective? Yes!

Python and Jupyter

Show all Pandas columns

pd.set_option(\'display.max_colwidth\', -1)

Increase Width of Jupyter Notebook

# Add this to the first cell of your notebook
from IPython.core.display import display, HTML
display(HTML("<style>.container { width:90% !important; }</style>"))

Install Dependencies

pip install -r requirements.txt

Display a full numpy array

np.set_printoptions(threshold=np.inf)

Automatically Reload Modules for Jupyter

# add to beginning of notebook
%load_ext autoreload
%autoreload 2

Creating a new Jupyter Notebook

import numpy as np
from matplotlib import pyplot as plt
from scipy import interpolate
import matplotlib.image as mpimg
import os
import PIL.Image as Image
%load_ext autoreload
%autoreload 2

Main Function

# wtf is this so hard to remember?
def main(): 
    print("hey there") 
if __name__=="__main__": 
    main() 

Raspberry Pi

SSH

touch ssh to enable ssh in /boot

WiFi

In /boot/wpa_supplicant.conf

country=US
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
ssid="NAME"
scan_ssid=1
psk="PASSWORD"
key_mgmt=WPA-PSK
}

network={
   ssid="TELLO-D8A5A9"
   key_mgmt=NONE
}

GPIO Cheatsheet

pinout

NMap to find devices

sudo nmap -sn 192.168.1.0/24

ROS

Build with Debug Flags

catkin_make -DCMAKE_BUILD_TYPE=Debug

Miscellaneous

Get GTK Thumbnails back

sudo apt install gnome-icon-theme

Video Thumbnail Previews in Dolphin

sudo apt install ffmpegthumbs mplayerthumbs kffmpegthumbnailer kio-extras
# and then enable Previews by going to Dolphin Preferences

sudo apt install kdenetwork-filesharing libsmbclient samba smbclient
# right click to Share folder after this

Change to libinput for touchpad

Uninstall synaptics.

Fresh Install

zoom code slack
geany mendeleydesktop

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