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POWriting a portable command line wrapper in C
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copied!<p>I'm writing a perl module called <a href="http://github.com/schwern/perl5i" rel="noreferrer">perl5i</a>. Its aim is to fix a swath of common Perl problems in one module (using lots of other modules).</p> <p>To invoke it on the command line for one liners you'd write: <code>perl -Mperl5i -e 'say "Hello"'</code> I think that's too wordy so I'd like to supply a perl5i wrapper so you can write <code>perl5i -e 'say "Hello"'</code>. I'd also like people to be able to write scripts with <code>#!/usr/bin/perl5i</code> so it must be a compiled C program.</p> <p>I figured all I had to do was push "-Mperl5i" onto the front of the argument list and call perl. And that's what I tried.</p> <pre><code>#include <unistd.h> #include <stdlib.h> /* * Meant to mimic the shell command * exec perl -Mperl5i "$@" * * This is a C program so it works in a #! line. */ int main (int argc, char* argv[]) { int i; /* This value is set by a program which generates this C file */ const char* perl_cmd = "/usr/local/perl/5.10.0/bin/perl"; char* perl_args[argc+1]; perl_args[0] = argv[0]; perl_args[1] = "-Mperl5i"; for( i = 1; i <= argc; i++ ) { perl_args[i+1] = argv[i]; } return execv( perl_cmd, perl_args ); } </code></pre> <p>Windows complicates this approach. Apparently programs in Windows are not passed an array of arguments, they are passed all the arguments as a single string and then do their own parsing! Thus something like <code>perl5i -e "say 'Hello'"</code> becomes <code>perl -Mperl5i -e say 'Hello'</code> and Windows can't deal with the lack of quoting.</p> <p>So, how can I handle this? Wrap everything in quotes and escapes on Windows? Is there a library to handle this for me? Is there a better approach? Could I just not generate a C program on Windows and write it as a perl wrapper as it doesn't support #! anyway?</p> <p>UPDATE: Do be more clear, this is shipped software so solutions that require using a certain shell or tweaking the shell configuration (for example, <code>alias perl5i='perl -Mperl5i'</code>) aren't satisfactory.</p>

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