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Remove all but one specific file

Download all PDFs from an authenificated website
Replace *** with the appropiate values

follow the content of all files in a directory
The `-q' arg forces tail to not output the name of the current file

find geographical location of an ip address
I save this to bin/iptrace and run "iptrace ipaddress" to get the Country, City and State of an ip address using the http://ipadress.com service. I add the following to my script to get a tinyurl of the map as well: URL=`lynx -dump http://www.ip-adress.com/ip_tracer/?QRY=$1|grep details|awk '{print $2}'` lynx -dump http://tinyurl.com/create.php?url=$URL|grep tinyurl|grep "19. http"|awk '{print $2}'

Grab IP address on machine with multiple interfaces
Instead of hard-coding in a check to scrape info from ifconfig based on a specific interface, do it in a more portable way. This works really well if you switch between wired, wireless, bluetooth or even VPN connections. You can get your current IP in a script (since it'll be something like tun0 instead of eth0 or wlan1). This uses a well known public ip address 8.8.8.8, but it doesn't actually connect to it, it just shows you the route it would take.

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Drop or block attackers IP with null routes
Someone might attack on your system. You can drop attacker IP using IPtables. However, you can use route command to null route unwanted traffic. A null route (also called as blackhole route) is a network route or kernel routing table entry that goes nowhere. Matching packets are dropped (ignored) rather than forwarded, acting as a kind of very limited firewall. The act of using null routes is often called blackhole filtering.

Create a file of a given size in linux

gag version of current date

Rename all (jpg) files written as 3 number in 4 numbers.
Useful if you have a list of images called 1 2 3 4 and so on, you can adapt it to rewrite it as 4 (in this example) 0-padded number.


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