date does not support pipes

[Philip Rogers]

Hi,

`date` seems not to support reading from stdin.
So if you want the "last data modification" date of a file, in ISO8601 
format at the seconds level, you have to:

stat --format "%Y" check.txt | { read ts; date -d@"$ts"; }

Instead of:

stat --format "%Y" check.txt | date

This is inconvenient.

Would it be possible to implement reading from stdin in date?

Best,
Philip