Ubuntu technical problems and solutions reference, a modern cookbook.
Gpg encryption is cool. It’s so cool, that I want to keep all my important files (that means back-up files) encrypted on my external storage.
Using gpg is fairly straight forward:
1) Generate a private key.
After answering some standard questions, the key is ready.
Note: You better not forget the password you choose, or else your encrypted files are lost forever.
2) Check you key:
This will display a list of all available keys.
3) Encrypt a file
gpg --encrypt --recipient 'key name' foo.txt
This will generate the encrypted file: foo.txt.gpg
4) Decrypt a file
gpg --output foo2.txt --decrypt foo.txt.gpg
foo2.txt file will be created.
So, until now I presented a quick guide to encrypt/decrypt a file. However, this wasn’t enough for me. I wanted to go a little further. I wanted to be able to encrypt folders as well, and the possibility to delete the original file, and keep only the encrypted one. So, I though I write my own function.
And so, tec was born.
In short tec stands for: tar, encrypt, clean. Long description: Tarballs and encrypts the TARGET using gpg (GnuPG) encrypton. Optionally it deletes the TARGET.
Just copy tec.sh into /usr/bin, and you’re good to go.
cd <download directory> sudo cp tec.sh /usr/bin
For general help, type:
# with delete option, to delete the original file, and keep the encrypted one tec.sh -dr <key> <file> # without delete option tec.sh -r <key> <file>
The project is in it’s early phases. Currently it only encrypts. For decryption the standard gpg commands have to be used. I plan to maintain the function, and try to add as much functionality as I can.
Recently I was faced with a new issue/challenge: adding custom man pages for a custom/user defined command. This being said, I started to dig into the configuration and structure of the man command.
I will not go too deep into the man theory, there is always Google for it, or the official manual pages:
As I now know, after reading documentation, there are 9 section of documentation for each command. So, it means separate documentation file for each section.
In the following example I will create custom documentation for section 1 (Executable user programs and shell commands) and section 4 (Information on device files). I call the command dummy.
#The following commands create the default structure for custom man pages cd ~/ mkdir ownman; mkdir ownman/man1; mkdir ownman/man4 cd ownman/man1 vi dummy.1 # Add some documentation here. Example: 1) Documentation for section 1 cd ../man4 vi dummy.4 # Add some documentation here. Example: 1) Documentation for section 4
Now that the structure is in place, the man pages for the the dummy command can be called. The -M option has to be used in order to specify the location of the man pages for the specific command.
man -M ~/ownman dummy 1) Documentation for section 1 Manual page dummy(1) line 1/66 (END) (press h for help or q to quit)
The default section is 1, so it’s not necessary to be specified here. With specification, the command looks like this:
man -M ~/ownman 4 dummy 1) Documentation for section 4 Manual page dummy(4) line 1/66 (END) (press h for help or q to quit)
The structure and the call is in place now. But still, it could be tiresome sometimes to remember the path to the man pages, especially if one were to declare multiple locations.
To add the ~/ownman location to the locations man is looking at by default, the configuration file needs to be edited. On Ubuntu this file is: /etc/manpath.config (for Red Hat and Red Hat derivatives, like CentOS and Fedora, the configuration file for man is /etc/man.config)
# need sudo rights for this, as the owner of the file is root sudo vi /etc/manpath.config
Edit the file by adding a new entry in the MANDATORY_MANPATH section.
If there is a need to specify different man pages path for different command paths, another edit needs to be made, further down in the file. A new entry for MANPATH_MAP
MANPATH_MAP ~/custom_commands_location ~/ownman
Now the simple, straight forward command can be called:
man dummy 1) Documentation for section 1 Manual page dummy(1) line 1/66 (END) (press h for help or q to quit)