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From: ted@loft.tnolan.com (Ted Nolan <tednolan>)
Newsgroups: comp.lang.c
Subject: Re: Command line globber/tokenizer library for C?
Date: 10 Sep 2024 22:13:06 GMT
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In article <87ldzzyyus.fsf@nosuchdomain.example.com>,
Keith Thompson  <Keith.S.Thompson+u@gmail.com> wrote:
>ted@loft.tnolan.com (Ted Nolan <tednolan>) writes:
>> I have the case where my C program is handed a string which is basically
>> a command line.
>>
>> Is there a common open source C library for tokenizing and globbing
>> this into an argc/argv as a shell would do?  I've googled, but I get
>> too much C++ & other language stuff.
>>
>> Note that I'm not asking for getopt(), that comes afterwards, and
>> I'm not asking for any variable interpolation, but just that a string
>> like, say
>>
>> 	hello -world "This is foo.*" foo.*
>>
>> becomes something like
>> 	
>> 	my_argv[0]	"hello"
>> 	my_argv[1]	"-world"
>> 	my_argv[2] "This is foo.*"
>> 	my_argv[3] foo.h
>> 	my_argv[4] foo.c
>> 	my_argv[5] foo.txt
>>
>> 	my_argc = 6
>>
>> I could live without the globbing if that's a bridge too far.
>
>What environment(s) does this need to run in?
>
>I don't know of a standard(ish) function that does this.  POSIX defines
>the glob() function, but it only does globbing, not word-splitting.
>
>If you're trying to emulate the way the shell (which one?) parses
>command lines, and *if* you're on a system that has a shell, you can
>invoke a shell to do the work for you.  Here's a quick and dirty
>example:
>
>#include <stdlib.h>
>#include <stdio.h>
>#include <string.h>
>int main(void) {
>    const char *line = "hello -world \"This is foo.*\" foo.*";
>    char *cmd = malloc(50 + strlen(line));
>    sprintf(cmd, "printf '%%s\n' %s", line);
>    system(cmd);
>}
>
>This prints the arguments to stdout, one per line (and doesn't handle
>arguments with embedded newlines very well).  You could modify the
>command to write the output to a temporary file and then read that file,
>or you could use popen() if it's available.
>
>Of course this is portable only to systems that have a Unix-style shell,
>and it can even behave differently depending on how the default shell
>behaves.  And invoking a new process is going to make this relatively
>slow, which may or may not matter depending on how many times you need
>to do it.
>
>There is no completely portable solution, since you need to be able to
>get directory listings to handle wildcards.

Yeah, that's the kind of thing I was hoping to avoid, and probably more
than I want to get into, but thanks!

>
>A quick Google search points to this question:
>
>https://stackoverflow.com/q/21335041/827263
>"How to split a string using shell-like rules in C++?"
>
>An answer refers to Boost.Program_options, which is specific to C++.
>Apparently boost::program_options::split_unix() does what you're looking
>for.
>
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