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View the latest astronomy picture of the day from NASA.
Substitute feh for the image viewer of your choice. display (part of imagemagick) seems to be a popular choice.

Block all FaceBook traffic

Extract busiest times from apache access log
Analyze an Apache access log for the time period with most activity and display the hit count, requesting IP and the timestamp. May help detect a brute force dos attack.

a function to find the fastest DNS server
http://public-dns.info gives a list of online dns servers. you need to change the country in url (br in this url) with your country code. this command need some time to ping all IP in list.

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

extract email adresses from some file (or any other pattern)
find all email addresses in a file, printing each match. Addresses do not have to be alone on a line etc. For example you can grab them from HTML-formatted emails or CSV files, etc. Use a combination of $...|sort|uniq$ to filter them.

Get the SAN (subjectAltName) of a site's certificate.
Based on http://stackoverflow.com/questions/13127352/checking-alternative-names-for-a-san-ssl-cert Replace "facebook.com" with the desired hostname.

Fixes Centos 6.2 yum's metalink certificate errors
Fix's centos 6.2 yum's error: could not get metalink https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=x86_64 error was 14: PYCURL ERROR 77 - "Problem with the SSL CA cert (path? access rights?)" Error: Cannot retrieve metalink for repository: epel-source. Please verify its path and try again

Display a block of text with AWK
I find this terribly useful for grepping through a file, looking for just a block of text. There's "grep -A # pattern file.txt" to see a specific number of lines following your pattern, but what if you want to see the whole block? Say, the output of "dmidecode" (as root): $ dmidecode | awk '/Battery/,/^$/' Will show me everything following the battery block up to the next block of text. Again, I find this extremely useful when I want to see whole blocks of text based on a pattern, and I don't care to see the rest of the data in output. This could be used against the '/etc/securetty/user' file on Unix to find the block of a specific user. It could be used against VirtualHosts or Directories on Apache to find specific definitions. The scenarios go on for any text formatted in a block fashion. Very handy.


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