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Gets the last string of previous command with !$
It helps you save a lot of writing :-)

Verify if user account exists in Linux / Unix

Write comments to your history.
A null operation with the name 'comment', allowing comments to be written to HISTFILE. Prepending '#' to a command will *not* write the command to the history file, although it will be available for the current session, thus '#' is not useful for keeping track of comments past the current session.

Get AWS temporary credentials ready to export based on a MFA virtual appliance
You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token. This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use: `awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'` You must adapt the command line to include: * $MFA_IDis ARN of the virtual MFA or serial number of the physical one * TTL for the credentials

Using vim to save and run your python script.
This will save and execute your python script every time your press the F5 function key. It can also be added to your .vimrc: autocmd BufRead *.py nmap :w^M:!python % NOTE: the ^M is not just caret-M, it can be created by type: ctrl-v ctrl-m

extracts 64 bytes of random digits from random lines out of /dev/random sent to stdio
Use this the next time you need to come up with a reasonably random bitstring, like for a WPA/WPA2 PSK or something. Takes a continuous stream of bytes coming from /dev/urandom, runs it through od(1), picking a random field ($0 and $1 excluded) from a random line and then prints it.

Remove comments in XML file
In Redhat, xmlstarlet is called just xml which can be found in xmlstarlet RPM.

Quick searching with less

Compare directories via diff
http://hints.macworld.com/article.php?story=20070408062023352

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"


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