AnonyMonk suggested avoiding the shell for numerous very good reasons -- some of which would likely be those I would cite: if you use the shell and the external program, you've increased complexity; likely have opened some exploitable security gaps, and added overhead for your server. Unless you think the variety of conversions done by the external program outweigh all of those, heed AM's advice.
And, in any case, be aware you're reinventing the wheel! Is there some really valid reason to create and invent/install your own wheels, gears, and interfaces when a simple search -- for "unit conversions" or even "conversions" will turn up many existing (and mostly, free) services?
And, please, read the instructions around the text-entry box. Use <p>...</p> around paragraphs; <c>...</c> around code and data. <pre> tags make your nodes hard to read or bork the rendering for some Monks.
Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
Read Where should I post X? if you're not absolutely sure you're posting in the right place.
Please read these before you post! —
Posts may use any of the Perl Monks Approved HTML tags:
You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
- a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
Link using PerlMonks shortcuts! What shortcuts can I use for linking?
See Writeup Formatting Tips and other pages linked from there for more info.
| & || & |
| < || < |
| > || > |
| [ || [ |
| ] || ] ||