Dear Maintainer, Quoth Issue 8 Draft 2.1 (unchanged for a long time), XCU, pr, STDOUT: -- >8 -- 104141 In the POSIX locale, the <output of date> field, representing the date and time of last modification 104142 of the input file (or the current date and time if the input file is standard input), shall be 104143 equivalent to the output of the following command as it would appear if executed at the given 104144 time: 104145 date "+%b %e %H:%M %Y" 104146 without the trailing <newline>, if the page being written is from standard input. If the page 104147 being written is not from standard input, in the POSIX locale, the same format shall be used, but 104148 the time used shall be the modification time of the file corresponding to file instead of the current 104149 time. When the LC_TIME locale category is not set to the POSIX locale, a different format and 104150 order of presentation of this field may be used. -- >8 -- RATIONALE: -- >8 -- 104203 The <output of date> field in the −l format is specified only for the POSIX locale. As noted, the 104204 format can be different in other locales. No mechanism for defining this is present in this volume 104205 of POSIX.1-202x, as the appropriate vehicle is a message catalog; that is, the format should be 104206 specified as a ``message’’. -- >8 -- (the -l thing appears to be an error). Why, then: -- >8 -- $ echo | pr -f 2023-04-25 23:16 Page 1 $ echo | LC_ALL=C pr -f 2023-04-25 23:16 Page 1 $ echo | LC_ALL=POSIX pr -f 2023-04-25 23:16 Page 1