Difference between timestamps

slayer_1994 · 04-05-2017, 09:33 AM

Hi guys

Tried executing this code but didn't seem to like it not 100% sure why

Code:

current_time=`date`
last_defect_file_recieved=`date -d @1489662376`

(stat --printf '%Y' $current_time; printf ' - '; stat --printf '%Y\n' $last_defect_file_recieved) | bc -lq

When I go to execute the script I get:

Quote:

[rp1cem@wycvlapph036 self_monitoring]$ ./test.sh
stat: cannot stat `Wed': No such file or directory
stat: cannot stat `Apr': No such file or directory
stat: cannot stat `5': No such file or directory
stat: cannot stat `15:33:15': No such file or directory
stat: cannot stat `BST': No such file or directory
stat: cannot stat `2017': No such file or directory
stat: cannot stat `Thu': No such file or directory
stat: cannot stat `Mar': No such file or directory
stat: cannot stat `16': No such file or directory
stat: cannot stat `11:06:16': No such file or directory
stat: cannot stat `GMT': No such file or directory
stat: cannot stat `2017': No such file or directory
(standard_in) 1: syntax error

Any particular reason for this?

pan64 · 04-05-2017, 09:35 AM

try to use ": "$current_time"

ondoho · 04-05-2017, 11:05 AM

not sure which shell you are using, but on my bash 4.4.12:

Code:

$> printf '%Y' "$(date)"
bash: printf: `Y': invalid format character

also why don't you use

Code:

date '+%s'

- much easier to do calculations with, and presumably 1489662376 already is in that format.

slayer_1994 · 04-07-2017, 03:08 AM

Hi ondoho

I understand what you are trying to say but 1489662376 is also the name of the file, so if the file executes I presume this number will change again?

As you can see below now the file has changed its name as the execution date changed:

Quote:

4/07/17 09:05:45.864 AM BST [INFO] [TimPollThreadPool.Thread6] [Manager.com.timestock.tess.services.tim.TimIo] File 'Wynyard_MTP_Primary-defect-14915523440000159519.xml' read, length=37791

And if I execute this on the timeline:

Quote:

[rp1cem@wycvlapph036 logs]$ date -d @1491552344
Fri Apr 7 09:05:44 BST 2017

So is there anyway of doing this?

Cheers

michaelk · 04-07-2017, 05:55 AM

In this case printf is an option of the stat command and not bash.

If you want to find the difference between timestamps they need to be in seconds.

The difference between now and Thu Mar 16 06:06:16 2017 in seconds.

Code:

echo "$(date '+%s')-1489662376" | bc -lq
1900076

The difference between now and Thu Mar 16 06:06:16 2017 in days.

Code:

echo "scale=0; ($(date '+%s')-1489662376)/3600/24" | bc -lq
21

Shadow_7 · 04-07-2017, 07:24 AM

Code:

#!/bin/bash

CURRENTDATE=$(date +%s)
OTHERDATE=$(date -d @1489662376 +%s); # redundant to use +%s on the epoch date
DIFFDATE=$(($CURRENTDATE-$OTHERDATE))
echo -n "Seconds: "$DIFFDATE" - "
date -d @$DIFFDATE +%Y%m%d-%H:%M:%S

exit 0

No need for printf or bc. Bash math $(( )) and date can replace most of that. Although you'd probably want to -1970 from the year (%Y) for the "difference". And $( ) replaces ` ` with an advantage of being more readable and nest-able. The default output of date is what makes up that list of cannot stat errors. Although your (stat ; stat) part probably needs a leading $ for $(stat ; stat), not that that would give desired results.

$ date +"%a %b %e %R:%S %Z %Y"
$ date

michaelk · 04-07-2017, 08:12 AM

Code:

date -d @$DIFFDATE +%Y%m%d-%H:%M:%S

The output is the absolute date for the number of seconds since the epoch and not the relative difference between timestamps although the number of days should be correct if using %j.

It depends on what the OP is trying to accomplish.

slayer_1994 · 04-12-2017, 05:53 AM

Hi Guys

Tried using the above command & it helped a lot.

I used man date to get a better understanding and saw their were other options

I used "+%F" so a full date for example and my return was the following:

[rp1cem@wycvlapph036 self_monitoring]$ ./test.sh
Seconds: 2331840 - 1970-01-28

Any particular reason why it says 1970 when the seconds is 26 days?

Quote:

CURRENTDATE=$(date +%s)
OTHERDATE=$(date -d @1489662376 +%s); # redundant to use +%s on the epoch date
DIFFDATE=$(($CURRENTDATE-$OTHERDATE))
echo -n "Seconds: "$DIFFDATE" - "
date -d @$DIFFDATE +%F
exit 0
~

Cheers
Alex

michaelk · 04-12-2017, 06:11 AM

In a nutshell time is basically a counter with 0 being 00:00 1 January 1970 UTC. This is known as epoch time which can differ between operating systems and applications that use date functions.

date -d @$DIFFDATE +%F converts the difference in seconds to an absolute date/time with reference to the epoch time which is why the year is 1970.

pan64 · 04-12-2017, 06:12 AM

you can put set -xv at the beginning of your script to see what's happening (that will not solve anything, just will print a lot of debug information)
DIFFDATE=$(($CURRENTDATE-$OTHERDATE))
you can remove those $

Shadow_7 · 04-12-2017, 07:42 AM

Quote:

Originally Posted by Shadow_7

...Although you'd probably want to -1970 from the year (%Y) for the "difference"...

The epoch date is 1970/01/01 at 00:00:00 when it's value is 0. Or 1969/12/31 at 23:59:59 for a lot of databases that store unset dates as -1. Basically using the epoch value for date math returns the deference relative to the epoch date for value 0.

michaelk · 04-12-2017, 10:34 AM

Quote:

...Although you'd probably want to -1970 from the year (%Y) for the "difference"...

By using %j option the date command outputs the day of the year (i.e 1-365) which is easier then trying to subtract 1970 or when the difference exceeds 31 days