Boot parameters of the running kernel in Linux

Let's say I need to find out with what parameters did the kernel boot?

The following command will give you the answer:

cat /proc/cmdline

For example:

janeiros@harlie:~$ cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-3.0.0-32-generic-pae root=/dev/mapper/harlie-root ro quiet

Endianness mnemotechnic

A long time ago I had a difficult time trying to remember the differences between Big Endian and Little Endian. I came out with this little trick to make it easier to remember: associate Low with 0.

In Big Endian, you store the most significant byte in the smallest address. In Little Endian, you store the least significant byte in the smallest address.

http://en.wikipedia.org/wiki/Endianness

Guava Files class

Sometimes you are still in the Java 1.6 land and you just to want to read the entire file into a list. Guava can help you:

File file = new File("trades_3.txt");
List<String> lines = Files.readLines(file, Charset.defaultCharset());

The Files class doc.

Foundation and Empire

1. Part I: The General
1. Search for Magicians
2. The Magicians
3. The Dead Hand
4. The Emperor
5. The War Begins
6. The Favorite
7. Bribery
8. To Trantor
9. On Trantor
10. The War Ends
2. Part II The Mule
11. Bride and Groom
12. Captain and Mayor
13. Lieutenant and Clown
14. The Mutant
15. The Psychologist
16. Conference
17. The Visi-Sonor
18. Fall of the Foundation
19. Start of the Search
20. Conspirator
21. Interlude in Space
22. Death on Neotrantor
23. The Ruins of Trantor
24. Convert
25. Death of a Psychologist
26. End of the Search

IPTABLES

# List the rules with line numbers,
# the -n disables the DNS reverse lookup
iptables -n --list --line-numbers

# Block a specific IP
iptables -A INPUT -s 192.168.0.1 -j DROP

# Allow SSH for a specific IP
iptables -A INPUT -s 192.168.0.2 -p tcp -m tcp --dport 22 -j ACCEPT

# Delete a rule based on its number
iptables -D INPUT 8

# Insert rule before other certain one
# For example before line # 3
iptables -I INPUT 3 -s 192.168.0.2 -p tcp -m tcp --dport 22 -j ACCEPT

Java 8 installation on Fedora 14

1. Download Java SDK/JRE from Oracle: http://www.oracle.com/technetwork/java/javase/downloads/server-jre8-downloads-2133154.html. (I selected the server version).
2. Extract the files into /usr/local/java. (I created the java directory).
3. Use the alternatives program to create the necessary links:
• [root@Fedora-test ~]# alternatives --install /usr/bin/java java /usr/local/java/jdk1.8.0_20/bin/java 20000
• Run the alternatives config command:

[root@Fedora-test ~]# alternatives --config java

Select the option for Java 8

• Test it:

[root@Fedora-test ~]# java -version
java version "1.8.0_20"
Java(TM) SE Runtime Environment (build 1.8.0_20-b26)
Java HotSpot(TM) 64-Bit Server VM (build 25.20-b23, mixed mode)

The following link was useful: http://www.dafoot.co.uk/index.php/menuitemcomputing/linux/101-fedora-12-alternatives-program-to-manage-java-runtimes-jdkjre

VIM's REGEXPs

http://vimregex.com/