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Create a random file of a certain, and display progress along the way.
SIZE is the number of gigabytes and the file name is at the end. Random data is generated by encrypting /dev/zero, similar to other techniques posted on here.

Convert CSV to JSON
Replace 'csv_file.csv' with your filename.

Temporarily ignore mismatched SSH host key
This command will bypass checking the host key of the target server against the local known_hosts file. When you SSH to a server whose host key does not match the one stored in your local machine's known_hosts file, you'll get a error like " WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!" that indicates a key mismatch. If you know the key has legitimately changed (like the server was reinstalled), a permanent solution is to remove the stored key for that server in known_hosts. However, there are some occasions where you may not want to make the permanent change. For example, you've done some port-forwarding trickery with ssh -R or ssh -L, and are doing ssh user@localhost to connect over the port-forwarding to some other machine (not actually your localhost). Since this is usually temporary, you probably don't want to change the known_hosts file. This command is useful for those situations. Credit: Command found at http://linuxcommando.blogspot.com/2008/10/how-to-disable-ssh-host-key-checking.html. Further discussion of how it works is there also. Note this is a bit different than command #5307 - with that one you will still be prompted to store the unrecognized key, whereas this one won't prompt you for the key at all.

Add your public SSH key to a server in one command
Just run the command, type your password, and that's the last time you need to enter your password for that server. This assumes that the server supports publickey authentication. Also, the permissions on your home dir are 755, and the permissions on your .ssh dir are 700 (local and remote).

Open up a man page as PDF (#OSX)
Simply pass an argument to the script to convert the manual page to a PDF: $man2pdf drutil

Quickly ping range of IP adresses and return only those that are online
Tested in Debian, ymmv. - c 1 : send only one ping;; -W 1: wait for one second and then exit ping, assuming target IP is not available; change as needed (-W 0.5 for half a second, smaller or greater value depending on network speed/latency)

Easily decode unix-time (funtion)
More recent versions of the date command finally have the ability to decode the unix epoch time into a human readable date. This function makes it simple to utilize this feature quickly.

Using numsum to sum a column of numbers.
if you, like me, do not have the numsum, this way can do the same.

burn initial session on a growable DVD using growisofs
replace "directory name to burn on DVD" with actual directory name that you want to copy on DVD

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


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