the usage of shell command `awk`:

(1) awk '{print}' employee.txt:
print everything in file `employee.txt`

(2) awk '/manager/ {print}' employee.txt:
print every line in file `employee.txt` that contains the word `manager`

(3) awk '{print $1,$4}' employee.txt:
print the 1st and 4th column of the file.

additional usage:
https://www.geeksforgeeks.org/awk-command-unixlinux-examples/

#systemProgramming