[Bug 1858883] Re: date utility format unexpectedly changed after upgrade from bionic to focal

[Mike Pontillo]

Thanks for taking a look. Yes, it looks like the `date` utility now
observes locale-based defaults, such as the new default:

$ date
Wed 25 Mar 2020 09:47:47 AM PDT

Here are some other combinations I tried:

$ LC_TIME="" date
Wed 25 Mar 2020 09:47:53 AM PDT

(setting LC_TIME to an empty string has no effect; the LC_TIME value
most likely obtains a default value based on a different setting.)

The following variations produce the (formerly, at least) expected
output:

$ LC_TIME="C" date
Wed Mar 25 09:47:59 PDT 2020

$ LC_ALL="C" date
Wed Mar 25 09:48:25 PDT 2020

$ LANG="C" date
Wed Mar 25 09:52:08 PDT 2020

This post suggests that LC_ALL should be set to C if the output of these
utilities is meant to be read by computers:

https://unix.stackexchange.com/a/87763/4295

So while this new default does have the potential to cause regressions
in users' scripts (and could be considered a regression in that sense),
the fix is to correctly set LC_ALL=C in when the `date` utility is
invoked in situations where its output is intended to be parsed.

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https://bugs.launchpad.net/bugs/1858883

Title:
  date utility format unexpectedly changed after upgrade from bionic to
  focal

Status in coreutils package in Ubuntu:
  New

Bug description:
  After upgrading my Bionic system to Focal, I noticed a significant
  change in the output of the `date` utility. This could potentially
  cause regressions for those who are relying on a consistent date
  format when using `date` in shell scripts.

  EXPECTED BEHAVIOR
  =================

  I expected to see the same date format that can be seen on Ubuntu
  releases (at least) from Trusty through Bionic:

  $ date -u
  Wed Jan  8 21:00:14 UTC 2020

  ACTUAL BEHAVIOR
  ===============

  On Focal (and Eoan) the following date format is seen by default:

  $ date -u
  Wed 08 Jan 2020 09:00:14 PM UTC

  Note the differences in zero-padding, whitespace, placement of the
  year, and the extraneous "PM" (I had expected to see a 24-hour time).

  FURTHER DETAILS
  ===============

  This machine was originally on Bionic and has been upgraded to
  development releases between Bionic and Focal.

  $ locale
  LANG=en_US.UTF-8
  LANGUAGE=
  LC_CTYPE="en_US.UTF-8"
  LC_NUMERIC="en_US.UTF-8"
  LC_TIME="en_US.UTF-8"
  LC_COLLATE="en_US.UTF-8"
  LC_MONETARY="en_US.UTF-8"
  LC_MESSAGES="en_US.UTF-8"
  LC_PAPER="en_US.UTF-8"
  LC_NAME="en_US.UTF-8"
  LC_ADDRESS="en_US.UTF-8"
  LC_TELEPHONE="en_US.UTF-8"
  LC_MEASUREMENT="en_US.UTF-8"
  LC_IDENTIFICATION="en_US.UTF-8"
  LC_ALL=

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