According to wikipedia, <i>cal</i> was in First Edition Unix, back in 1971.  You can assume it&#x27;s been used in scripts and it would be hard to change default behavior now, or any time in the last 30 years for that matter.<p>I&#x27;ve used it myself in scripts to find Julian day numbers, to count days-within-months, etc. -- for old science data -- before there were more robust ways to do this stuff.<p>It&#x27;s hard to insert DWIM behaviors into old command-line utilities, because &quot;what I mean&quot; is not clear.