How do I convert an epoch timestamp to a human readable format on the cli?

How do I convert an epoch timestamp to a human readable format on the cli? I think there’s a way to do it with date but the syntax eludes me (other ways welcome).

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

On *BSD:

date -r 1234567890

On Linux (specifically, with GNU coreutils ≥5.3):

date -d @1234567890

With older versions of GNU date, you can calculate the relative difference to the UTC epoch:

date -d '1970-01-01 UTC + 1234567890 seconds'

If you need portability, you’re out of luck. The only time you can format with a POSIX shell command (without doing the calculation yourself) line is the current time. In practice, Perl is often available:

perl -le 'print scalar localtime $ARGV[0]' 1234567890

Method 2

date -d @1190000000 Replace 1190000000 with your epoch

Method 3

If your epoch time is in milliseconds instead of seconds, remove the last three digits before passing it to date -d:

$ date -d @1455086371603
Tue Nov  7 02:46:43 PST 48079     #Incorrect

This gives incorrect data. Remove the last three digits.

$ date -d @1455086371
Tue Feb  9 22:39:31 PST 2016      #Correct after removing the last three digits. You may remove and round off the last digit too.

Method 4

Custom format with GNU date:

date -d @1234567890 +'%Y-%m-%d %H:%M:%S'

Or with GNU awk:

awk 'BEGIN { print strftime("%Y-%m-%d %H:%M:%S", 1234567890); }'

Linked SO question: https://stackoverflow.com/questions/3249827/convert-from-unixtime-at-command-line

Method 5

With bash-4.2 or above:

printf '%(%F %T)Tn' 1234567890

(where %F %T is the strftime()-type format)

That syntax is inspired from ksh93.

In ksh93 however, the argument is taken as a date expression where various and hardly documented formats are supported.

For a Unix epoch time, the syntax in ksh93 is:

printf '%(%F %T)Tn' '#1234567890'

ksh93 however seems to use its own algorithm for the timezone and can get it wrong. For instance, in Britain, it was summer time all year in 1970, but:

$ TZ=Europe/London bash -c 'printf "%(%c)Tn" 0'
Thu 01 Jan 1970 01:00:00 BST
$ TZ=Europe/London ksh93 -c 'printf "%(%c)Tn" "#0"'
Thu Jan  1 00:00:00 1970

Method 6

$ echo 1190000000 | perl -pe 's/(d+)/localtime($1)/e' 
Sun Sep 16 20:33:20 2007

This can come in handy for those applications which use epoch time in the logfiles:

$ tail -f /var/log/nagios/nagios.log | perl -pe 's/(d+)/localtime($1)/e'
[Thu May 13 10:15:46 2010] EXTERNAL COMMAND: PROCESS_SERVICE_CHECK_RESULT;HOSTA;check_raid;0;check_raid.pl: OK (Unit 0 on Controller 0 is OK)

Method 7

The two I frequently use are:

$ perl -leprint scalar localtime 1234567890
Sat Feb 14 00:31:30 2009

and

$ tclsh
% clock format 1234567890
Sa Feb 14 00:31:30 CET 2009

Method 8

With zsh you could use the strftime builtin:

strftime format epochtime

      Output the date denoted by epochtime in the format specified.

e.g.

zmodload zsh/datetime
strftime '%A, %d %b %Y' 1234567890

Friday, 13 Feb 2009

There’s also dateconv from dateutils:

dateconv -i '%s' -f '%A, %d %b %Y' 1234567890

Friday, 13 Feb 2009

keep in mind dateutils tools default to UTC (add -z your/timezone if needed).

Method 9

In PowerShell:

(([System.DateTimeOffset]::FromUnixTimeMilliSeconds($unixtime)).DateTime).ToString("s")

Method 10

You could also use a little C program for printing the datetime in the format that can be directly parsed by shell

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

int main(int argc, char * argv[]) {

    if (argc==1) { 
        return 1;
    }

    struct tm input_tm;
    char * formatStr  = "YEAR=%YnMON=%mnDAY=%dnHOUR=%HnMIN=%MnSEC=%S";
    size_t formatSize = strlen(formatStr) + 2;
    char * output     = (char *)malloc(sizeof(char)*formatSize);

    strptime(argv[1],"%s",&input_tm);
    strftime(output, formatSize, formatStr, &input_tm);

    printf("%sn",output);
    free(output);
    return 0;
}

usage:

#compile
clang -o epoch2datetime main.c

#invoke
eval `./epoch2datetime 1450196411`
echo $YEAR $MON $DAY $HOUR $MIN $SEC
#output
#2015 12 16 00 20 11

Method 11

Wouldn’t be a real solution without a little node.js:

epoch2date(){
    node -p "new Date($1)"
}

add that to ~/.bash_aliases and make sure its sourced in ~/.bashrc with . ~/.bash_aliases

if [ -f ~/.bash_aliases ]; then
    . ~/.bash_aliases
fi

To get node on your system goto http://nvm.sh and run the curl command. It’ll install node version manager (nvm) which allows you to switch versions of node.

Just type nvm ls-remote and pick a version to nvm install <version>.

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0