Yes I wrote about this on my blog: [ Is a Builtin, But [[ Is Part of the Language http://www.oilshell.org/blog/2016/10/12.html http://www.oilshell.org/blog/20

Yes I wrote about this on my blog: [ Is a Builtin, But [[ Is Part of the Language http://www.oilshell.org/blog/2016/10/12.html http://www.oilshell.org/blog/2016/10/12.html I didn't know that before I started implementing a shell :) I knew that [ could be a builtin or /usr/bin/[, but not about the difference between [ and [[.