Gawk also provides more recent Bell Labs awk extensions, and some GNU-specific extensions. Once you are proficient with Bison, you may use it to develop a wide range of language parsers, from those used in simple desk calculators to complex programming languages. Anyone familiar with Yacc should be able to use Bison with little trouble. A very bloated editor. It can do just about anything.
Some people do almost all of their work in emacs every day.
Others think those people are completely looney. You know it, you love it, you use it. Many people find it extremely useful in creating logos and other graphics for web pages. The GIMP has many of the tools and filters you would expect to find in similar commercial offerings, you would expect to find in similar commercial offerings, and some interesting extras as well. GNU tar allows you to store many files in a single tar file which describes the names and contents of the constituent files.