On 3/15/25 09:11, Otto Moerbeek wrote: > On Sat, Mar 15, 2025 at 08:55:18AM +0100, Christian Schulte wrote: > >> On 3/15/25 07:37, Otto Moerbeek wrote: >>> On Sat, Mar 15, 2025 at 07:29:39AM +0100, Christian Schulte wrote: >>> >>>> Hi @misc, >>>> >>>> I recently stumbled upon an issue with GNU printf(1). I was using >>>> echo(1) in a testsuite.at on OpenBSD successfully, but that failed on >>>> linux badly. The OpenBSD man page of echo(1) contains this sentence: >>>> >>>> Where portability is paramount, use printf(1). >>>> >>>> So I replaced echo(1) with printf(1). This leads to... >>>> >>>> OpenBSD: >>>> >>>> x500$ printf -0 >>>> -0x500$ printf -something >>>> -somethingx500$ >>>> >>>> which is the expected output. On linux I get >>>> >>>> schulte@vps:~$ printf -0 >>>> -bash: printf: -0: invalid option >>>> printf: usage: printf [-v var] format [arguments] >>>> schulte@vps:~$ printf -something >>>> -bash: printf: -s: invalid option >>>> printf: usage: printf [-v var] format [arguments] >>>> >>>> Would you rate this a bug in GNU printf(1)? >>>> >>>> -- >>>> Christian >>>> >>> >>> No, i would rate as a usage error. Use -- to separate options form the >>> rest of the arguments. >>> >>> print -- -0 >>> >>> -Otto >> >> Thanks. Adding -- everywhere should make it portable. Would you mind >> explaining the following to me as well? >> >> For example: >> >> x500$ echo -n \\u0041 >> \u0041x500$ >> >> Expected output. >> >> x500$ printf -- \\u0041 >> printf: unknown escape sequence `\u' >> u0041x500$ >> >> x500$ printf -- \\\u0041 >> printf: unknown escape sequence `\u' >> u0041x500$ >> >> x500$ printf -- \\\\u0041 >> \u0041x500$ >> >> Why does printf(1) require four backslashes to yield the same output? >> The man page just mentions: >> >> \\ Write a backslash character. >> >> I would have expected \\\\ to write two backslash characters. Is this >> related to the shell, or to the command? >> >> -- >> Christian >> > > It's the shell plus echo does not care about backslashes while printf > does, and \u is an unknown escape sequence to printf. See the shell > man page of how shell quoting and backslashes work (Command syntax and > Quoting sections). > > -Otto >
No idea how many shells there are around doing things the way the do. Running "grep printf configure" on the configure script generated by the GNU toolchain shows a lot of "printf" without --. Running "grep echo configure" seems they use echo when needing to use backslashes. Maybe I am just a bit too paranoid about portability. Just pushed it to github. May it blow up on everyone else but me. Funny thing is that after nearly 3 decades of Java development I must admit how blind, lazy and incompetent one gets. Thanks a lot for helping me. -- Christian
