Re: Command line globber/tokenizer library for C?

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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