What does this egrep command do?egrep '[^A-M][0-9]+' /etc/passwdSo far I think it searches for any file in /etc/passwd that starts with A-M and includes the number(s) 0-9. Is that right?
What does this egrep command do?
grep;regular expression
^ at the beginning of an expression means beginning of line.  However, ^ inside a bracket expression matches everything not in that expression.  So, for example, while [abcd] matches the letters a, b, c, or d, the expression [^abcd] matches everything other than those letters.So the expression you've got matches anything not A-M, followed by 1 or more digits.The following lines would all match that expression:mmmmmz0912300this is a very long line that includes the number 1.Because they all contain a digit preceded by something that is not in the range A-M.