Can you explain in detail what happened here on this command?
grep -nw '^root' /etc/passwd
What is the use of ^ and '? Please give me examples and be detailed cuz all I'm hearing is that it's the beginning of the line. I don't understand what each of those special characters means.
How would I go about using wc, grep and ^ to find out the number of non-root processes running on my system?
grep -nw '^root' /etc/passwd
It reads the /etc/passwd file line-by-line and filters out all those lines that ^=begin with the -w=complete word "root". So, for example the line
root:x:0:0:root:/root:/bin/bash
To see all processes on a system, you could use ps aux. and it will show lines like this
root 22866 0.0 [...] 0:00 [kworker/1:0]
As you can see, the lines start with a username. If you pipe the ps aux output through grep, you can use the same RegEx from above, to filter out all lines that do not start with "root".
Use -v to invert pattern matching, so that grep -vw '^root' finds all lines that don't begin with a complete word "root".
ps aux | grep -vw '^root' | wc -l
Finally, wc -l counts the number of lines it receives. So that is the number of all lines from ps aux that do not begin with "root".