Difference to Regular Expressions. And you can use them in a number of different places: After the == in a bash [[ expr ]] expression. * All of the extglob quantifiers supported by bash were supported by ksh88. Since 3.0, Bash supports the =~ operator to the [[ keyword. Regular expression to match a line that doesn't contain a word. grep , expr , sed and awk are some of them.Bash also have =~ operator which is named as RE-match operator.In this tutorial we will look =~ operator and use cases.More information about regex command cna be found in the following tutorials. Regular expressions are great at matching. Non greedy text matching and extrapolating in bash. means any character in pattern matching? R-egular E-xpression MATCH-ing (the first many times I read the word "rematch", I just could not help my thoughts drifting back to Hulk Hogan taking on André the Giant at WrestleMania IV- those were the days...) is performed using commands on the form: Sed command that would ignore any commented match. 1. In man bash it says: Pattern Matching Any character that appears in a pattern, other than the special pattern characters described below, matches itself. And while I'm comparing glob patterns to regular expressions, there's an important point to be made that may not be immediately obvious: glob patterns are just another syntax for doing pattern matching in general in bash. ... How to check if a string contains a substring in Bash. 1. Related. I know that BASH =~ regex can be system-specific, based on the libs available -- in this case, this is primarily CentOS 6.x (some OSX Mavericks with Macports, but not needed) Thanks! 6. 2. Where in the documentation does it say that . One easy way to exclude text from a match is negative lookbehind: w+b(?