GNU/Linux Notes on Christopher Carter

dd

Wed, 16 Apr 2025 00:00:00 +0000

dd is a program for converting and copying files, with sometimes disastrous consequences. It is nicknamed “disk destroyer” for a reason. Be careful.

For tasks like copying an .iso to a drive to make bootable media, consider using something like Ventoy.

Formatting a Drive With An `.iso`

You can use use dd is to copy .iso image files to block media (like a USB drive) to make the media bootable. This is done by running:

Deploy a Website With rsync

Wed, 16 Apr 2025 00:00:00 +0000

You can deploy a static website easily using rsync. No CI/CD, git integration, Netlify, or other modern devops bloat required!

On the remote machine, create a directory under your user, e.g. ~/www/mysite. Then create a symlink so the website can be served by your webserver, e.g. from /var/www/mysite.

sudo ln -sT ~/www/mysite /var/www/mysite

On the local machine, assuming your static site lives at mysite/ set up ssh with the remote server and use the following rsync command:

ffmpeg

Wed, 16 Apr 2025 00:00:00 +0000

ffmpeg is for video stuff. The basic principle is to take a video/audio input, and transform it to a video/audio output:

ffmpeg -i <input> <output>

Trimming a Video

A video can be trimmed using the following pattern:

ffmpeg -ss 00:00:40 -to 00:01:16 -i input.mp4 output.mp4

-ss is the start time of the clip you wish to cut, -to is the end time of the clip, and -i is the input video file.

Formatting Block Storage

Wed, 16 Apr 2025 00:00:00 +0000

Formatting a block storage device, like a hard drive or a flash drive, is the process of making the drive usable for storage. It consists of two steps:

Format the partitions of the drive. These are logical sections of memorythat can have distinct filesystems, mount points, etc.
Make filesystems on the partitions. This allows your computer to write files to the partitions when the device is mounted.

Format the Partitions

Use fdisk to manage the partitions on the block device. Start the process with

Mounting Devices

Wed, 16 Apr 2025 00:00:00 +0000

To access an external storage device, like a flash drive, a hard drive, a mobile phone, etc., the device must be mounted to a location on your filesystem.

Block Devices

To mount a block device (hard drive, flash drive, etc.), use the mount syscall:

sudo mount <device> <mountpoint>

where <device> is a device e.g. /dev/sdb1 and <mountpoint> is a directory on your device to mount to. To unmount, simply do:

sudo umount <device>
# or
sudo umount <mountpoint>

Where should my mountpoint be?

If it is removable media, mount it under /media. /media often has seperate subdirectories unter it for each removable medium, e.g. /media/floppy, /media/cdrom, /media/zip, etc. I have /media/usb for my usb drives.

SSH

Wed, 16 Apr 2025 00:00:00 +0000

ssh, short for “secure shell”, is a protocol to make an encrypted connection to a remote server. Per the name, the most common use case is to connect via shell, but it is also used by applications like git, scp, etc. to make secure connections and transfer data.

Using SSH

You initiate a connection to a server over ssh by opening a terminal and running

ssh <username>@<server>

for example

ssh mike@example.com

Depending on the server configuration, you will be prompted for your password for the account you have on the server. Upon successfuly authentication, a shell session on the remote server will appear in your terminal, and you can interact as you would in a normal terminal session.

GPG

Tue, 16 Apr 2024 00:00:00 +0000

GPG, short for “GNU Privacy Guard” allows you to encrypt and sign data according to the OpenPGP (or just “PGP”) standard. It can be used to verify software downloads and encrypt email.

It can be difficult to find a single place that enumerates all the essential GPG concepts and terminology in one place. I recommend reading the website for GPG, as well as Email Self-Defense, and of course, man gpg.

Generating a GPG key

run gpg --full-generate-key
Select RSA and RSA.
Enter 4096 for key size.
Enter an expiration date, e.g. 2y for 2 years.
Pick a passphrase for the key.

You can edit a gpg key by running gpg --edit-key.

GNU/Linux Notes on Christopher Carter

dd

Formatting a Drive With An .iso

Deploy a Website With rsync

ffmpeg

Trimming a Video

Formatting Block Storage

Format the Partitions

Mounting Devices

Block Devices

Where should my mountpoint be?

SSH

Using SSH

GPG

Generating a GPG key

Formatting a Drive With An `.iso`