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get all Google ipv4/6 subnets for a iptables firewall for example (updated version)
google has added 2 more netblocks...

Find out if a module is installed in perl
Shows the path if the module is installed or exit quietly (to simply avoid the 'No documentation found' msg).

function to compute what percentage of X is Y? Where percent/100 = X/Y => percent=100*X/Y
This function make it easy to compute X/Y as a percentage. The name "wpoxiy" is an acronym of "what percentage of X is Y"

Annoying PROMPT_COMMAND animation
unset PROMPT_COMMAND to disable.

List all Samba user name

Generate hash( of some types) from string
No need to install yet another program when openssl is already installed. :-)

Calculate days on which Friday the 13th occurs (inspired from the work of the user justsomeguy)
Friday is the 5th day of the week, monday is the 1st. Output may be affected by locale.

Show GCC-generated optimization commands when using the "-march=native" or "-mtune=native" switches for compilation.
You can tell GCC to automatically select optimization commands and produce optimized code for the local machine (the one compiling the code), but you can't normally see what switches have been selected and used unless you append a "-v" and pause compilation.

This command can be used to extract the IP address of the network.
can be used within a script to configure iptables for example: iface=$2 inet_ip=`ifconfig "$iface" | grep inet | cut -d: -f2 | cut -d ' ' -f1` ipt="sudo /sbin/iptables" ......................... ---------------------------------------------------------------------------------------------------------------- $ipt -A INPUT -i $iface ! -f -p tcp -s $UL -d $inet_ip --sport 1023: --dport 3306 -m state --state NEW,ESTABLISHED -j ACCEPT ---------------------------------------------------------------------------------------------------------------- ----------------------------------------------------------------------------------------------------------------- $ipt -A OUTPUT -o $iface -p tcp -s $inet_ip -d $UL --sport 3306 --dport 1023: -m state --state ESTABLISHED,RELATED -j ACCEPT -----------------------------------------------------------------------------------------------------------------

Batch resize all images in the current directory that are bigger than 800px, height or weight.
You need to install imagemagick. On Debian type: # apt-get install imagemagick


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