On 7/22/19 12:56 PM, k...@munnari.oz.au wrote: > Configuration Information [Automatically generated, do not change]: > Machine: x86_64 > OS: netbsd > Compiler: gcc > Compilation CFLAGS: -O2 -D_FORTIFY_SOURCE=2 -I/usr/include -Wno-parentheses > -Wno-format-security > uname output: NetBSD jinx.noi.kre.to 8.99.30 NetBSD 8.99.30 (1.1-20190114) > #9: Mon Jan 14 13:29:08 ICT 2019 > k...@onyx.coe.psu.ac.th:/usr/obj/testing/kernels/amd64/JINX amd64 > Machine Type: x86_64--netbsd > > Bash Version: 5.0 > Patch Level: 7 > Release Status: release > > Description: > POSIX specifies that printf(1) has no options, and by not
Correct that there are no POSIX-mandated options,... > specifying that it is intended to comply with XBD 12.2 effectivly > says that it is not. That is, in printf, the first arg is > always the format string, whatever it contains. ...but wrong that it is not allowed to have options as extensions. XBD 12.2 states "Some of the standard utilities do not conform to all of these guidelines; in those cases, the OPTIONS sections describe the deviations." and "The utilities in the Shell and Utilities volume of POSIX.1-2017 that claim conformance to these guidelines shall conform completely to these guidelines as if these guidelines contained the term "shall" instead of "should"." Then further in XSH, POSIX states in XSH 1.4 (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap01.html) that "Default Behavior: When this section is listed as "None.", it means that the implementation need not support any options. Standard utilities that do not accept options, but that do accept operands, shall recognize "--" as a first argument to be discarded." and again for 'printf' (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/printf.html) "OPTIONS None." You are correct that for some utilities, POSIX does not require compliance with the Utility Syntax Guidelines (XSH 2.14 states that the special shell builtins do not comply by default without explicit mention, which is the opposite of other utilities that DO comply by default without explicit mention). But since printf is not one of the special builtins, and does not document an exemption, it must comply with the relevant Utility Syntax Guidelines. > > So > printf --- should print three - chars to stdout Not so. The utility syntax guidelines state that you have invoked unspecified behavior, because you started an argument with '-' but which is not intended to be parsed as an option. The implementation may treat it as a literal string, but may equally treat it as an attempt to parse it as the first '-' requesting an option, the second '-' being the option character being requested, but treating it as an error since no option named '-' exists. If you want to output a literal string containing three dashes, you MUST write 'printf -- ---'. > printf -%d 3 should print -3 to stdout Not so. POSIX doesn't require extension options, but also does not forbid them. Bash happens to have extension options, so your command line is not portable, and it is not a bug in bash. > Please, let's try to avoid losing control of printf like what > happened to echo, stick to the requirements of POSIX where they > apply and actually speficy the output required. POSIX already specifies the bash behavior as permitted. There is nothing to change here but your broken command lines. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org
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