• Find duplicates: fdupes (fdupes . -r > ~/duplicates.dat)

• create archive:
     tar -cvf name-of-archive.tar /path/to/directory-or-file
• create archive with compression:
     tar -czvf name-of-archive.tar.gz /path/to/directory-or-file
• create archive and delete files after archive would be created
     tar -cvf name-of-archive.tar.gz --remove-files /path/to/directory-or-file

• rsync by default uses ssh to transfer files between machines
• --remove-source-files - To MOVE files from one machine to another (delete source after moving file) use:
     rsync --remove-source-files <source> <destination >
  where destination is another directory or another directory on another machine
• --partial This is another switch that is particularly useful when transferring large files over the internet. If rsync gets interrupted for any reason in the middle of a file transfer, the partially transferred file is kept in the destination directory and the transfer is resumed where it left off once the rsync command is executed again. When transferring large files over the internet (say, a couple of gigabytes), theres nothing worse than having a few second internet outage, blue screen, or human error trip up your file transfer and having to start all over again.
• -P this switch combines --progress and --partial, so use it instead and it will make your rsync command a little neater.
• -z or --compress This switch will make rsync compress file data as its being transferred, reducing the amount of data that has to be sent to the destination. Its actually a fairly common switch but is far from essential, only really benefiting you on transfers between slow connections, and it does nothing for the following types of files: 7z, avi, bz2, deb, g,z iso, jpeg, jpg, mov, mp3, mp4, ogg, rpm, tbz, tgz, z, zip.
• -h or --human-readable - If youre using the --progress switch, youll definitely want to use this one as well. That is, unless you like to convert bytes to megabytes on the fly. The -h switch converts all outputted numbers to human-readable format, so you can actually make sense of the amount of data being transferred.

• Join two lines: J ([shift] J)
• Display status line: ^g
• Undo: u
• Write part of the file: :12,15w NewFileName
• Forward search: /string
• Backward search: ?string

• date +"%Y-%m-%d %T"
  The result:
     2017-06-27 14:30:18

Autossh is a program to start a copy of ssh and monitor it, restarting it as necessary should it die or stop passing traffic.
Typical use:
   autossh -M 0 -o "ServerAliveInterval 30" -o "ServerAliveCountMax 3" pi@hampton.ddns.net -L 4000:localhost:3389
Details

• crontab file location: /var/spool/cron/crontabs. Each user has separate file
• timing syntax: <minute> <hour> <day of month> <month> <day of week>
  Example:
     10 * * * * /usr/bin/php /www/virtual/username/cron.php > /dev/null 2>&1
• You can use multiple numbers separated by commas. E.g.: to run three times every hour, at minutes 0, 10 and 20:
     0,10,20 * * * * [command]
• Division operator is also used. This will run 12 times per hour, i.e. every 5 minutes:
     */5 * * * * [command]
• Dash can be used to specify a range. This will run once every hour between 5:00am and 10:00am:
     0 5-10 * * * [command]
• Also there is a special keyword that will let you run a cron job every time the server is rebooted:
     @reboot [command]

Details

To enaable read/write access to NTFS device, install ntfs-3g package:
sudo apt-get update
sudo apt-get install ntfs-3g

Then you will need to power cycle the Raspberry Pi. I'm not yet sure why there is a difference between a reboot and a power cycle, but you must power cycle the Raspberry Pi. That means turn it off, wait 5+ seconds, then turn it back on. Since my drive was powered by the same USB hub-thingey as my Pi, I used the switch to turn off the Pi and the drive, waited 5 seconds, and then turned both of them back on.

Details

• NFS on RPi - including troubleshooting

Virtual Linux on Windows

Youtube instructions

1. Start diskpart as administrator
      start cmd ad administrator and type diskpart
2. type list disk
      progran will diskpay list of physical disks attached to the computer
3. Select disk which you are going to mess
       in my case it is "Disk 1"
   type: select disk 1
4. CHECK THAT YOU SELECTED correct disk
      detail disk
      program will display information about selected disk - check it
5. Delete all partitions:
      clean
6. create partition primary
7. active
8. format fs=ntfs quick (instead of ntfs can be another format)
9. exit