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Difference Between grep and egrep
The main difference between grep and egrep is that grep is a command that allows searching content according to the given regular expression and displaying the matching lines while egrep is a variant of grep that helps to search content by applying extended regular expressions to display the machining lines.
The operating system is the core of the entire computer system. It works as the interface between the user and the hardware. Furthermore, it performs memory management, process handling, task scheduling and many more. UNIX is a stable operating system. Linux is a free and open source operating system that is based on UNIX. These operating systems provide the opportunity for the users to enter commands to the Command Line Interface (CLI) to accomplish tasks. There is a large number of commands with options. Two of them are grep and egrep. The grep allows to search patterns using regular expressions whereas egrep allows using extended regular expressions. Overall, egrep allows searching multiple patterns at a time using a single command easily.
After 104 commits from six different people, GNU grep was released Saturday, reports Phoronix.
The biggest change? “It's now made more clear that if you are still relying on the egrep and fgrep commands, it's past due for switching to just grep with the appropriate command-line arguments.” The egrep and fgrep commands have been deprecated since 2007. Beginning with GNU Grep 3.8 today, calling these commands will now issue a warning to the user that instead they should use grep -E and grep -F, respectively.
Eventually, GNU Grep will drop the egrep / fgrep commands completely but there doesn't seem to be a firm deadline yet for when that removal will happen.
From grep's updated manual: 7th Edition Unix had commands egrep and fgrep that were the counterparts of the modern 'grep -E' and 'grep -F'. Although breaking up grep into three programs was perhaps useful on the small computers of the 1970s, egrep and fgrep were not standardized by POSIX and are no longer needed. In the current GNU implementation, egrep and fgrep issue a warning and then act like their modern counterparts; eventually, they are planned to be removed entirely.
If you prefer the old names, you can use use your own substitutes, such as a shell script…
Other notable changes from the release announcement:
The confusing GREP_COLOR environment variable is now obsolescent. Instead of GREP_COLOR='xxx' use GREP_COLORS='mt=xxx'
Regular expressions with stray backslashes now cause warnings