Week 13, Intro to Unix lab 2016

Content

• questions
• awk - reading output of pipe
  • mycommand = "seq 10"
  • getline mycommand - read one row of stdout of mycommand to $0
  • ! ( mycommand | getline ) - test if reading failed (EOF)
• collaborative test - hackathon
  • task - simplified postfix calculator
    • with four variables:
      • last - read only
      • X, Y, Z - read and write
    • with four operations
      • + x / - =' - the last one is assign, not equal
    • examples
      • x prints 0 - variables are initialized to 0
      • 3 4 + prints 7
      • 1 2 + 3 * prints 9
      • 1 2 3 + * fails and does not print 5 - simplified postfix you need to write 2 3 + 1 *
      • 3 last + prints 6 - last is initialized at the first argument at start
      • 3 last + last + prints 12
      • X 3 = prints 3 and assing x to 3
      • X 3 = X x assing x to 3 and prints 9
  • how to divide work to pairs
    • define interfaces
• Recommended reading - Shell v příkladech, Libor Forst, 2010 - part 6 - case studies