Linux Blog

Database explorer and query tool

CrunchyFrog is a database explorer and query tool for GNOME.

Currently PostgreSQL, MySQL, Oracle, SQLite3 databases and LDAP servers are supported for browsing and querying. More databases can be added using the plugin system.

This application requires GTK+ version 2.12.x. Other dependencies include:
For a (almost) complete list of dependencies see http://code.google.com/p/crunchyfrog/wiki/Requirements

Download : here

How To increase the MAX file upload size in PHP

There is a variable in your php.ini file (Location of this file may differ for different distribution but is mainly located in /etc directory or in /etc/php directory, try to find this file)

Open this php.ini file in any text editor and locate the section "File Uploads", now in this section, first, you need to enable the upload of file by modifying the variable "file_uploads = On" and next you can increase the upload limit to any value that you may required by modifying the value of "upload_max_filesize = 20M".

As you can see here in my case I have made the limit to 20MB, you can put your any required value here and restart the apache server to take the effect.

HTML to PS/PDF converter

htmldoc is a powerful simple-to-use tool which converts HTML to Postscript, PDF, or indexed HTML output. It provides a graphical user interface for manual document conversion -- useful for tasks such producing printed manuals from web pages -- but it can also be used as a filter.

Installing from the command line (Fedora): yum install htmldoc
Installing using the graphical installer: Applications > Office/Productivity > htmldoc
Menu location after installation: Office > HTMLDOC
Command: /usr/bin/htmldoc
website: http://www.htmldoc.org/

Using GPG

1. Key Generation

gpg # Initialize GPG for this user (e.g. create ~/.gnupg). Only have to run once.
gpg --gen-key # Start key generation process. Follow prompts.

2. Viewing Keys

gpg --list-keys # View public keys
gpg --list-secret-keys # View private keys

3. Exporting Public Keys

gpg --export # Exports key in binary format
gpg --export --armor # Export in a usable, ASCII format

4. Importing Public Keys

gpg --import /path/to/public/key/file

5. Encrypting a Message

gpg --encrypt --armor --recipient message_file

6. Decrypting a Message

gpg encrypted_message_file

You will be prompted for the filename to use for the output of the decryption process.

7. Encrypting with a Symmetric Key

gpg --symmetric --armor message_file

8. Signing and Encrypting a Message

gpg --sign --encrypt --armor --recipient message_file

9. Creating a Detached Signature

gpg --detach-sign --armor message_file # Sender
gpg --verify message_file.asc message_file # Recipient

10. Signing Another's Public Key

Alice is going to sign Bob's key.

# First, user A must do:
gpg --sign-key user_B
gpg --export --armor user_B > B.key

# Then, user_b must do:
gpg --import B.key

Execute more than one commands

Executing the second command only if the first is successful

To do this you would type: command1 && command2

command2 will be executed if command1 successfully completes (if command1 fails command2 won't be run). This is called a logical AND.

Executing the second command only if the first fails

To do this you would type: command1 || command2

command2 will be executed if command1 does not successfully completes (if command1 is successful command2 won't be run). This is called a logical OR.

Executing commands sequentially

To execute command sequentially regardless of the success/failure of the previous you simply type: command1; command2

command2 will execute once command1 has completed.