Ingo, I was always curious why you guys used perl. I love this mailing list! Thank you. Stay fly and dry.
Reese KN4NTU On Tue, Aug 05, 2025 at 02:43:36AM +0200, Ingo Schwarze wrote: > Hello Dan, > > Dan wrote on Tue, Aug 05, 2025 at 01:51:59AM +0200: > > > Scripting under ksh: does it exist a way to script a clear of the last > > three printed chars on the current line ? > > $ printf "this is a test\b\b\b \n" > this is a t > $ printf "this is a test"; printf "\b\b\b "; printf "\n" > this is a t > $ printf "this is a test"; sleep 10; printf "\b\b\b "; printf "\n" > this is a test <- cursor remains here > [10 seconds later, the output line changes to:] > this is a t > $ > > This is actually quite close to how the C code implementing ksh(1) > does this internally when it wants to delete the last three characters > printed: it simply write(2)s three backspace characters followed > by three space characters to standard output. Of course, that's > where the similarity ends; internally, it obviously does not use > printf(1) or echo(1) or anything similar. Just write(2). > > That said, if you want to do terminal manipulation of this kind, > then you almost certainly do not want to write your program in > the ksh(1) language. Instead, you want to write your program > in C and use curses(3) for cursor positioning and selective > updates of terminal window content. Or in another high-level > language that provides terminal manipulation facilities. > > Any *sh(1) scripting language is a very poor fit for writing > a program that wants to perform terminal manipulation. > Generally, do not write any program of significant size in *sh(1). > It is among the hardest languages to use securely; certainly, > writing good sh(1) or ksh(1) code is *much* harder than > writing good C code - so much so that i have already rewritten > some ksh(1) programs in perl(1) for the OpenBSD project to > make them more secure and less fragile. Writing good perl(1) > code is certainly harder to learn than writing good C code, > but perl(1) is still easier to use securely than *sh(1). > > Yours, > Ingo >
