Converting Date with Timezone in Unix Timestamp Shell/Bash

Converting date with timezone in UNIX timestamp Shell/Bash

You don't need to call date twice. Just call it once with TZ set to the timezone you want for that variable.

timesydney=$(TZ=Australia/Sydney date -d "$dateYMD" +%s)
timenyc=$(TZ=US/Eastern date -d "$dateYMD" +%s)

How to convert timestamps to dates in Bash?

On systems with GNU Coreutils >= 5.3.0, e.g. Linux you can use:

date -d @1267619929

Commandline to convert ISO8601 time to unix timestamp

Convert ISO Date/Time to Unix timestamp

date -d 'date' +"%s"

Example

   bash-# date -d 'Fri Dec  8 00:12:50 UTC 2017' +"%s"
   bash-# 1512691970

man -a date

   -d, --date=STRING
          display time described by STRING, not 'now'

   %s     seconds since 1970-01-01 00:00:00 UTC

Convert Unix timestamp to ISO Date/Time

date -Iseconds -d @<unix timestamp>

Example

   bash-# date -Iseconds -d @1512711426
   bash-# 2017-12-07T21:37:06-0800

man -a date

   -d, --date=STRING
          display time described by STRING, not 'now'

   -I[TIMESPEC], --iso-8601[=TIMESPEC]
          output  date/time  in  ISO 8601 format.  
          TIMESPEC='date' for date only (the default), 'hours',                             
          'minutes', 'seconds', or 'ns' for date and time to the 
          indicated precision.

How to convert DATE to UNIX TIMESTAMP in shell script on MacOS

man date on OSX has this example

date -j -f "%a %b %d %T %Z %Y" "`date`" "+%s"

Which I think does what you want.

You can use this for a specific date

date -j -f "%a %b %d %T %Z %Y" "Tue Sep 28 19:35:15 EDT 2010" "+%s"

Or use whatever format you want.

Bash: get date and time from another time zone

You could use

TZ=America/New_York date

or if you want to do date arithmetic you could use

date -d "+5 hours"

Converting Date and time to UNIX date format

Convert string datetime to datetime obj, and then retrieve timestamp.

from datetime import datetime
t = "2021/12/04 11:10:00.000"
dt = datetime.strptime(t, "%Y/%m/%d %H:%M:%S.%f")
dt.timestamp()

Output:

1638637800.0

SH: how to convert the date Nov 26 23:59:00 2022 GMT to timestamp?

The version of the date command that I have on my system (YMMV) will show us what it is doing if we add the --debug flag to our invocation...

$ date  -d "Nov 26 23:59:00 2022 GMT" +"%s" --debug
date: parsed date part: (Y-M-D) 2020-11-26
date: parsed time part: 23:59:00
date: parsed number part: year: 2022
date: parsed zone part: UTC+00
date: input timezone: parsed date/time string (+00)
date: using specified time as starting value: '23:59:00'
date: starting date/time: '(Y-M-D) 2022-11-26 23:59:00 TZ=+00'
date: '(Y-M-D) 2022-11-26 23:59:00 TZ=+00' = 1669507140 epoch-seconds
date: timezone: system default
date: final: 1669507140.000000000 (epoch-seconds)
date: final: (Y-M-D) 2022-11-26 23:59:00 (UTC)
date: final: (Y-M-D) 2022-11-27 07:59:00 (UTC+08)
1669507140

The debug log shows us the %s format will result in displaying seconds since epoch. Alternatively, nanosecond precision can be achieved using a modified format string (I added a .001 in the date string to prove it works):

$ date -d "Nov 26 23:59:00.001 2022 GMT" +"%s.%N" --debug
date: parsed date part: (Y-M-D) 2020-11-26
date: parsed time part: 23:59:00
date: parsed number part: year: 2022
date: parsed zone part: UTC+00
date: input timezone: parsed date/time string (+00)
date: using specified time as starting value: '23:59:00'
date: starting date/time: '(Y-M-D) 2022-11-26 23:59:00 TZ=+00'
date: '(Y-M-D) 2022-11-26 23:59:00 TZ=+00' = 1669507140 epoch-seconds
date: timezone: system default
date: final: 1669507140.001000000 (epoch-seconds)
date: final: (Y-M-D) 2022-11-26 23:59:00 (UTC)
date: final: (Y-M-D) 2022-11-27 07:59:00 (UTC+08)
1669507140.001000000

We can use a pipe to awk to round up to milliseconds for our final form (note I used .0005 in the date string here to show rounding):

$ date -d "Nov 26 23:59:00.0005 2022 GMT" +"%s.%N" | awk '{ printf("%d\n", int($0 * 1000) + (int($0 * 2000) % 2)) }'
1669507140001

One further note.... The following is the version of the date command I am using:

$ date --version
date (GNU coreutils) 8.30
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://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.

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