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diff current vi buffer edits against original file

Display usb power mode on all devices

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

List open TCP/UDP ports

check open ports without netstat or lsof

Create a temporary file
To create directory, use: $ tempdir=$(/bin/mktemp -d)

Read and write to TCP or UDP sockets with common bash tools
Ever needed to test firewalls but didn't have netcat, telnet or even FTP? Enter /dev/tcp, your new best friend. /dev/tcp/(hostname)/(port) is a bash builtin that bash can use to open connections to TCP and UDP ports. This one-liner opens a connection on a port to a server and lets you read and write to it from the terminal. How it works: First, exec sets up a redirect for /dev/tcp/$server/$port to file descriptor 5. Then, as per some excellent feedback from @flatcap, we launch a redirect from file descriptor 5 to STDOUT and send that to the background (which is what causes the PID to be printed when the commands are run), and then redirect STDIN to file descriptor 5 with the second cat. Finally, when the second cat dies (the connection is closed), we clean up the file descriptor with 'exec 5>&-'. It can be used to test FTP, HTTP, NTP, or can connect to netcat listening on a port (makes for a simple chat client!) Replace /tcp/ with /udp/ to use UDP instead.

Look for English words in /dev/urandom
* to get the English dictionary: wget http://www.mavi1.org/web_security/wordlists/webster-dictionary.txt

identify NEEDED sonames in a path
This works in combination with http://www.commandlinefu.com/commands/view/10496/identify-exported-sonames-in-a-path as it reports the NEEDED entries present in the files within a given path. You can then compare it with the libraries that are exported to make sure that, when cross-building a firmware image, you're not bringing in dependencies from the build host. The short version of it as can be seen in the same output is $ scanelf -RBnq -F "+n#f" $1 | tr ',' '\n' | sort -u

One line Perl Script to determine the largest file sizes on a Linux Server
This one line Perl script will display the smallest to the largest files sizes in all directories on a server.


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