The shell is generated, not written. There are mountains of generated shell configuration code out there due to the prevalence of autoconf, which relies on thes

The shell is generated, not written. There are mountains of generated shell configuration code out there due to the prevalence of autoconf, which relies on these M4 (a macro preprocessor) scripts to generate thousands of lines of unreadable shell script (which has to be portable). This is how a non negligible number of your tools are built.