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Module 1: terminal commands

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Module 1: Terminal first steps

  • Using terminal on the raspberry pi:
  • Start with ping:
  • ping sends a data packet to a machine on the internet, and tells you how long it takes to return, like sonar
  • try pinging 10.14.0.1 Time listed will be in milliseconds, so 1000 ms means one second
  • ping www.apple.com
  • Notice different ping times

Stopping stuff:

  • ctrl-c means cancel
  • ctrl-z means halt (stop everything, not gracefully)

Tracing around the internet:

traceroute www.apple.com (note hops and delays)

Evil stuff: ping flood attack:

ping flood, only use here as a test

sudo ping -f (notice that you have to use sudo, which means "superuser do" or treat me like computer god for this)

What's going on in your terminal:

  • who also whoami
  • last last command, also the up arrow
  • top lists all processes, useful with kill (see later)
  • history: shows recent commands like this, useful for retracing your steps or seeing who might have been in your machine:
    • 1 ping 10.14.0.1
    • 2 ping www.hpa.edu
    • 3 traceroute
    • 4 traceroute www.hpa.edu
    • 5 ifconfig
    • 6 ping 10.14.252.22
    • 7 sudo ping -f 10.14.252.22
    • 8 last
    • 9 who
    • 10 ping 10.14.252.47
    • 11 history
    • 12 ssh pi@10.14.252.47
    • 13 netstat
    • 14 man netstat
    • 15 man ping
    • 16 history

navigation commands:

  • cd change directory, usually followed by a directory name, like "cd var/www/html/"
  • ls list directory, see also ls -l which lists all files in long form. Try also ls -lh *human long form"
  • ls -la lists even invisible files (the -a flag means "all") You can also hide files by adding . to the beginning
  • pwd print working directory, shows where you are in the file system (directory)

Try navigating to the desktop this way:

  • pwd (print working directory, "where am I")
  • ls (shows what is at this level)
  • cd or cd .. (cd to a directory, cd .. means one level up)
  • Here is where your desktop is: /home/pi/Desktop

Shortcut:

cd /home/pi/Desktop

try ls and see what is there, should be nothing.

Creating a directory:

  • mkdir creates a directory
  • mkdir test
  • This should create a folder on your desktop called "test"
  • click on this to see a directory browser, go nuts

Permissions

  • ls -la will show you permissions in the format drwx, for directory, read, write and execute
  • read is 1, write is 2, execute is 4, so all added up 1+2+4 =7
  • chmod change "mod" or permissions of file, 777 is everything, see drwx format below and the 421 rule
  • You may also find this under chmod u+x on a file, which means make the file or program executable

Manual pages:

  • man pages are manual pages, so "man ping" would give you manual pages on the ping command
  • less means look into a file (contrast with "more")
  • * means wild card, so if you want to see all files ending in jpg, you would say *.jpg

Secure shell login:

ssh means secure shell login, like ssh pi@10.14.88.81

Mac specific commands:

  • fsck -yf after command-s startup (single user mode)
  • say command after ssh login


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