When I ask date(1) for the date "a day ago", I get a different result from when I ask date(1) for the date "1 day ago". The results differ by 3 hours.
If I ask for UTC time, the results differ by 1 hour. I'm not able to find anything in the manual to explain this difference. I realize making sense of a natural language specification of a date is complicated. Still, I wonder whether the difference in behavior is intentional and if so why. $ for dash_u in '' '-u' ; do for one in 1 a ; do date $dash_u -d "$one day ago" ; done ; done + date -d '1 day ago' Thu Oct 24 09:51:22 EDT 2019 + date -d 'a day ago' Thu Oct 24 06:51:22 EDT 2019 + date -u -d '1 day ago' Thu Oct 24 13:51:22 UTC 2019 + date -u -d 'a day ago' Thu Oct 24 14:51:22 UTC 2019 $ date --version date (GNU coreutils) 8.26 Copyright (C) 2016 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Written by David MacKenzie. If you think this is a bug and you'd like a fix, I'd be happy to supply one. Just let me know. Thanks. -Matt
