sp;<span class="string">"caml_sys_rename"</span><br>
&nbsp;&nbsp;<span class="keyword">external</span>&nbsp;getenv&nbsp;:&nbsp;string&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;string&nbsp;=&nbsp;<span class="string">"caml_sys_getenv"</span><br>
&nbsp;&nbsp;<span class="keyword">val</span>&nbsp;getenv_opt&nbsp;:&nbsp;string&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;string&nbsp;option<br>
&nbsp;&nbsp;<span class="keyword">external</span>&nbsp;command&nbsp;:&nbsp;string&nbsp;<span class="keywords