Commands using cat (514)

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Every Nth line position # (SED)
sed extract every nth line. Generic is: $ sed -n 'STARTPOSITION,${p;n;*LINE}' foo where n;*LINE = how many lines. thus p;n;n; is "for every 3 lines" and p;n;n;n;n; is "for every 5 lines"

Fetch the Gateway Ip Address
This is to fetch the Gateway Ip Address of a machine. Use the below format to put the value in a variable if you wish to find the gateway ip in a script $GATEWAY=$(netstat -nr | awk 'BEGIN {while ($3!="0.0.0.0") getline; print $2}')

recursive search and replace old with new string, inside files
Using -Z with grep and -0 with xargs handles file names with spaces and special characters.

VIM: Replace a string with an incrementing number between marks 'a and 'b (eg, convert string ZZZZ to 1, 2, 3, ...)

put command in a loop to keep trying a connection
This will keep trying to reconnect your netcat connection can be used with SSH or Telnet, just substitute nc for ssh or telnet very useful for troubleshooting VPNs were you want to send continuous packets towards a destination to trace.

Quick and dirty hardware summary
Quick and dirty hardware summary where lshw is not available. Requires util-linux, procps, pciutils, usbutils and net-tools, which should be preinstalled on most systems.

Function to output an ASCII character given its decimal equivalent

Decrypt exported android wallet keys for import into desktop client (LTC,FTC,BTC)

Play music from youtube without download

Decode base64-encoded file in one line of Perl
If you are in an environment where you don't have the base64 executable or MIME tools available, this can be very handy for salvaging email attachments when the headers are mangled but the encoded document itself is intact.


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