Every process has at least 3 way of communication:

  • STDIN
  • STDOUT
  • STDERR

Redirections <, >

** $echo “test message” > /tmp/file ** ** mail -s “mail test” < /tmp/file **

STDOUT of one command to STDIN of other use |

Screenshot 2023-09-18 at 21 54 08

To execute second command if first is successful &&

Screenshot 2023-09-18 at 21 56 45

Variables

prefixed with a dollar sign Screenshot 2023-09-18 at 22 14 06

referencing a variable ${var}

Screenshot 2023-09-18 at 22 18 48

back quotes executes content Screenshot 2023-09-18 at 22 21 22

Filters, cut command

Cut command in detail https://www.geeksforgeeks.org/cut-command-linux-examples/ Screenshot 2023-09-18 at 22 33 57 sort command Screenshot 2023-09-18 at 22 44 34 uniq command - print unique lines Screenshot 2023-09-18 at 22 47 08 wc - world counting Screenshot 2023-09-18 at 22 48 49


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