Home / ubuntu / Questions / 1211390
Accepted
Adalbert Hanßen
Asked: 2020-02-19 09:54:11 +0800 CST

Is it possible to let date return its result in ISO 8601 format by default

  • 772

I want to change the behavior of the command date (possibly by setting some proper environment variable) such that it returns its output as if it was invoked as

date --iso-8601=seconds
  1. Is that possible and how does one accomplish this?
  2. If one applies the searched-for trick, would it resrict the usage of the command date or would it still be possible to override my desired default behavior?
default date environment

2 Answers

  1. Best Answer

    bash "aliases" are the answer. Here's a snippet from my ~/.bash_aliases:

    #
# Various timestamping commands
# ds 15Aug27
alias ds="date +%y%b%d"
# timestamp "11May14-191416"
alias timestamp="date +%y%b%d-%H%M%S"
# today "20110514"
alias today="date +%Y%m%d"
# tshhmmss "11May14-191540"
alias tshhmmss="date +%y%b%d-%H%M%S"
# tshhmm "11May14-1916"
alias tshhmm="date +%y%b%d-%H%M"
# tsymd "2011-May-14"
alias tsymd="date +%Y-%b-%d"
# tsjou "18-11-01 01:55:28" for journalctl --since
alias tsjou="date '+%y-%m-%d %H:%M:%S'"
# tsiso "2020-02-18T13:31:37-05:00"
alias tsiso="date --iso-8601=seconds"

    The one you want is the last, tsiso.

    Aliases make date, among other commands, much more useful. Read man date;info date and you can do almost anything with date.

    • 1

  2. I found another way solving this problem and the similar one for ls:

    Add the following lines to the end of /etc/bash.bashrc:

    # 2020-02-23 hinzugefügt für Datumsformat ISO-8601 bei ls:
export TIME_STYLE=long-iso
alias ls='ls –color=auto'
# 2020-02-23 hinzugefügt für date (denn das reagiert nicht auf TIME_STYLE):
alias date='date -Iseconds'

    In order to work for ls, you have to log out and log on again.

    However, if you do it like this particular formatting e.g. to the second, you can't use any other formatting option for date any more to override it. It would be rejected as giving more than one formatting option. You can overcome this by prepending a backslash in order to unalias the command date, e.g.: \date -Ihours.

    Still then you have to unalias the command date in any script you use. Problems may arise if you use scripts written by someone esle unaware of date being modified!

    It would be nice if date would either also honour TIME_STYLE or just take the last option for each category if more than one is given. Then this would work seamless... Alas, things are different now!

    • 0