Commands using awk (1,418)

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Transform a portrait pdf in a landscape one with 2 pages per page
This is an example of the usage of pdfnup (you can find it in the 'pdfjam' package). With this command you can save ink/toner and paper (and thus trees!) when you print a pdf. This tools are very configurable, and you can make also 2x2, 3x2, 2x3 layouts, and more (the limit is your fantasy and the resolution of the printer :-) You must have installed pdfjam, pdflatex, and the LaTeX pdfpages package in your box.

Port Knocking!
Knock on ports to open a port to a service (ssh for example) and knock again to close the port. You have to install knockd. See example config file below. [options] logfile = /var/log/knockd.log [openSSH] sequence = 3000,4000,5000 seq_timeout = 5 command = /sbin/iptables -A INPUT -i eth0 -s %IP% -p tcp --dport 22 -j ACCEPT tcpflags = syn [closeSSH] sequence = 5000,4000,3000 seq_timeout = 5 command = /sbin/iptables -D INPUT -i eth0 -s %IP% -p tcp --dport 22 -j ACCEPT tcpflags = syn

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"

apt-get via sudo
An apt-get wrapper function which will run the command via sudo, but will run it normally if you're only downloading source files. This was a bit of an excuse to show off the framework of $ cmd && echo true || echo false ...but as you can see, you must be careful about what is in the "true" block to make sure it executes without error, otherwise the "false" block will be executed. To allow the apt-get return code to pass through, you need to use a more normal if/else block: $ apt-get () { if [ "$1" = source ]; then command apt-get "$@"; else sudo apt-get "$@"; fi }

list block devices
Shows all block devices in a tree with descruptions of what they are.

determine if tcp port is open
for udp nmap -sU -p 80 hostname

Count the number of deleted files
It does not work without the verbose mode (-v is important)

Clean up after a poorly-formed tar file
These days, most software distributed in tar files will just contain a directory at the top level, but some tar files don't have this and can leave you with a mess of files in the current folder if you blindly execute $ tar zxvf something.tar.gz This command can help you clean up after such a mistake. However, note that this has the potential to do bad things if someone has been *really* nasty with filenames.

check open ports without netstat or lsof

git remove files which have been deleted
This command handles git rm'ing files that you've deleted.


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