Linux

Network Tricks

Connecting to two networks - one Wi-Fi and one wired

Wi-Fi network has internet, wired does not. Then, disable the gateway of the Wired network for internet access.

Show the networks

$ ip route show

Smaller metric number means higher priority for the gateway

Remove the gateway of the wired network

$ sudo ip route del default via 192.168.1.1

chroot into a Raspberry Pi

Mount sequence

mount /dev/sdb3 /mnt
mount /dev/sdb2 /mnt/boot
mount /dev/sdb1 /mnt/boot/firmware
mount -o bind /proc /mnt/proc
mount -o bind /sys /mnt/sys
mount -o bind /dev /mnt/dev
mount -o bind /dev/pts /mnt/dev/pts
cp /usr/bin/qemu-arm-static /mnt/usr/bin
chroot /mnt

Doing stuff in chroot

Example: Fixing a broken apt install

dpkg --configure -a
apt -f install
exit

Unmount sequence

umount /mnt/dev/pts
umount /mnt/dev/
umount /mnt/sys
umount /mnt/proc
umount /mnt/boot/firmware
umount /mnt/boot/
umount /mnt

Gnome tricks

Creating a desktop launcher on Gnome

Install gnome-panel

sudo apt-get install --no-install-recommends gnome-panel

Open the Create Launcher dialog and enter the details for the launcher

sudo gnome-desktop-item-edit --create-new /usr/share/applications

Done.

Trimming a video

ffmpeg can be used to trim a video from a given start time to end time.

ffmpeg -i video.webm -ss 00:00:00 -t 00:05:04 -async 1 video-cut.webm

Create ebook from a website using Calibre

Some free books on the internet are available as HTML pages.
An epub file is simply an archive of HTML pages that can be treated as an ebook.
A book website can be stitched into an ebook using wget and calibre

wget -r --no-parent http://www.hpmor.com/
ebook-convert index.html hpmor.epub

X Window system tricks

Switch to Colemak layout in X window system

setxkbmap us -variant colemak

Natural scrolling

Run the following command, then logout and login.

echo "pointer = 1 2 3 5 4 6 7 8 9 10 11 12" >> ~/.Xmodmap