Linux

Linux Hints

Why I use RAID1 

Linux Quick Reference

Command Line Cheat Sheet

Summary of Linux commands from Linux Tidbits

Bash Tutorials for Beginners (Linux Handbook)

Bash Shell Scripting Tutorial (by Vivek Gite) 

   and vital collection of hints about Bash Script Pitfalls

Bash Notes for Professionals (book from Stack Overflow)

ExplainShell to interpret and adapt shell script commands

Basic Vim Commands 

Latex Basics

Online Latex Equation Editor  (generates bitmap)

The Curious coder's Guide to Git

Windsurfer Antenna (build you own and boost your Wi-Fi signal)

Useful Linux Commands 

(use ExplainShell to interpret and adapt these and other commands)

Using GnuPG and KGpg for encryption:

1. First generate a key pair:

   1. • KGpg: When you start for the first time, choose to always start at login, and to generate a key pair. After the first start, you can also open the Key Manager and go to the menu Keys/Generate Key Pair...

        • Give Name, Email and comment for user ID.

        • Choose expiration: 0 (never expires).

        • Choose the key length: 2048, for example.

        • Choose the algorithm: either RSA & RSA or DSA & ElGamal

        • Enter a Passphrase: note that a long sequence of unrelated words is easier to remember and harder to crack than a short sequence of mixed letters and symbols.

        • You can also generate a key pair from the command line with:

          • • gpg2 --gen-key

        • It takes a while for the system to generate sufficient entropy for a good quality key pair.

2. Now, you can export the public key and give it to others, so they can encrypt files that only you can decrypt. You also can export it to a key server, so others can more easily find it.

3. You can also right-click on the key and Export Secret Key, but make sure you encrypt the file and save it in a secure and hidden place. This secret key can be imported into KGpg at another machine to enable encryption and decryption with the same key pair.

4. To Trust your own key (or any imported key), double-click on it, change Owner trust to Ultimately and OK. You may have to refresh the list (F5) to see the Trust colour change. 

5. You can also set this key as the default key: right-click and select Set as Default Key.

6. To encrypt a file, right-click on it and select Actions / Encrypt File. In case of a text file, you can also right-click on KGpg and select Open Editor, then Open the text file and click on Encrypt. Select your Public Key from the list, then Save As, if you want a different name for the encrypted file. After saving the encrypted file, do not forget to delete the unencrypted version, in case you used different names.

7. You can also encrypt a file from the command line with:

   1. • gpg2 [-r userID] -e file.name

8. If no userID is given, the default key (your own) is used. The encrypted file is saved in the same directory as file.name.pgp .

9. To decrypt a file, right-click on it and choose Open with / KGpg. With this method, a copy of the decrypted file will be saved in the same directory. In case of a text file, you can also right-click on KGpg and select Open Editor, then Open the encrypted file and click on Decrypt. This second method does not create an unencrypted file on the disk, just on memory, and the unencrypted text disappears, when you close the Editor window.

10. You can also decrypt a file from the command line with:

    1. • gpg2 -d file.name.pgp > file.name

11. If you want to modify an encrypted text file, after opening it and decrypting with the KGpg Editor, do not forget to encrypt again the modified text before saving the encrypted file.