I am not sure I agree with the logic. On an absolute instruction count scale grep will often dwarf the instructions necessary for the higher level logic captured in the shell script. Insert appeal to andahls law here. Writing in some more optimal language often requires considerably more work, and if the marginal benefit of reducing a few forks is minuscule compared to grep performance, why would you do this?
It depends on where your hot path is. If you’re writing the kind of performance critical code where the different between ‘egrep’ and ‘grep -E’ matters, then you shouldn’t be writing it in $SHELL to begin with. Not just because of the expense fork()ing, but because Bash is interpreted, because each exec requires loading new code into your L1 cache, and so on. It’s just never going to be as quick as something written in most other languages with a mature regex library.
I’m not saying this as a criticism against shell scripting (I’m an author of an alternative $SHELL and shell scripting language, so do have a love for shell scripting). I’m saying it as a criticism against people who try to optimise against the wrong things.
I guess in a way we are “violently agreeing” (as some say) because your point about the engineering effort mattering more than micro-optimisations is an example of the right kind of optimisations. Which is what I’m also, albeit badly, trying to describe.
