According to wikipedia, cal was in First Edition Unix, back in 1971. You can assume it's been used in scripts and it would be hard to change default behavior n

According to wikipedia, cal was in First Edition Unix, back in 1971. You can assume it'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. I'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. It's hard to insert DWIM behaviors into old command-line utilities, because "what I mean" is not clear.