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Check if it's your binary birthday!
Print out your age in days in binary. Today's my binary birthday, I'm 2^14 days old :-) . This command does bash arithmatic $(( )) on two dates: Today: $(date +%s) Date of birth: $(date +%s -d YYYY-MM-DD) The dates are expressed as the number of seconds since the Unix epoch (Jan 1970), so we devide the difference by 86400 (seconds per day). . Finally we pipe "obase=2; DAYS-OLD" into bc to convert to binary. (obase == output base)

Get sunrise and sunset times
This will get the sunrise and sunset times of a specific location. To be able to determine $l you need to first go to http://weather.yahoo.com/ and look up your location. The last numbers in the URL will be the $l Instead of forecastrss?w=$l you can also use forecastrss?p=$l and use the RSS link of the city you found. Also see http://developer.yahoo.com/weather/ for more information

Find the package that installed a command

function to verify an IP address - can be used at the shell prompt or in a shell script
When processing IP addresses in the shell (or shell script) it is useful to be able to verify that the value of data is an IP address (an not some random string or non-sensible IP address).

Top 15 processes with the largest number of open files
See the summary.

Instantly load bash history of one shell into another running shell
By default bash history of a shell is appended (appended on Ubuntu by default: Look for 'shopt -s histappend' in ~/.bashrc) to history file only after that shell exits. Although after having written to the history file, other running shells do *not* inherit that history - only newly launched shells do. This pair of commands alleviate that.

find text in a file
this will find text in the directory you specify and give you line where it appears.

1+2-3+4-5+6-7 Series

create a backup for all directories from current dir
Create backup (.tar.gz) for all first-level directory from current dir.

[vim] Clear a file in three characters (plus enter)
% selects every line in the file. 'd' deletes what's selected. It's a pretty simple combination.


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