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Old 03-28-2017, 08:43 AM   #1
slayer_1994
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Registered: Feb 2017
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Date not returning


Hi There

I am trying to do the difference of two file dates, however when I do the some the return is blank.

Any help would be greatly appreciated.

Code:
current_time=`date +%s`
last_login_of_tim=`date -d @1489662376 +%s`

diff_sec=`(($current_time-$last_login_of_tim))`

echo $current_time
echo $last_login_of_tim
echo $diff_sec
Quote:
[rp1cem@wycvlapph036 self_monitoring]$ ./test.sh
1490704960
1489662376
Cheers
 
Old 03-28-2017, 08:53 AM   #2
schneidz
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try this:
Quote:
Originally Posted by slayer_1994 View Post
Hi There

I am trying to do the difference of two file dates, however when I do the some the return is blank.

Any help would be greatly appreciated.

Code:
current_time=`date +%s`
last_login_of_tim=`date -d @1489662376 +%s`

diff_sec=$(($current_time-$last_login_of_tim))

echo $current_time
echo $last_login_of_tim
echo $diff_sec


Cheers
 
1 members found this post helpful.
Old 03-28-2017, 08:59 AM   #3
rtmistler
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Doing math like that is your problem.

Try something like, and note that you need the white spaces around the minus sign:
Code:
diff_sec=`expr $current_time - $last_login_of_tim`
 
Old 03-28-2017, 08:59 AM   #4
slayer_1994
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Quote:
Originally Posted by schneidz View Post
try this:

Great thank you What was I doing wrong? I assume this is showing in seconds how would I show in minutes?
 
Old 03-28-2017, 10:40 AM   #5
Sefyir
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Your syntax for Arithmetic Expansion is incorrect. I suspect you are assuming that `command` == $(command) is equivalent in similar cases.
However, while Command Substitution may be implemented with `command` or $(command), Arithmetic Expansion is only implemented by doing $((expression))

Using `command` is poor form however. It's hard to read and cannot be nested.
 
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Old 03-28-2017, 01:52 PM   #6
ondoho
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also:
Quote:
Originally Posted by slayer_1994 View Post
Code:
diff_sec=$((current_time - last_login_of_tim))
 
Old 03-28-2017, 02:01 PM   #7
rtmistler
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An important point to observe here is that you did not know where the error resided in your script.

If you add a "set -xv" line near the start of the script, it would have enabled verbose output and informed you that there was a problem with your mathematical attempt. From there any of the offered solutions to fix that line are applicable.
 
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Old 03-28-2017, 02:27 PM   #8
Habitual
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Some date math in http://www.linuxquestions.org/questi...rt-4175544200/ may help.
 
Old 03-29-2017, 06:35 AM   #9
slayer_1994
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Hi Guys

Thanks for all your help on this much appreciated

Usually for time you take the first 10 characters of a files name, what if the file I am looking at has the date within it?
File 'Wynyard_MTP_Primary-btstats-2017-03-29-10:34:50.xml'

This is the file I want to do the same the difference between the dates but as it has the date already in it won't I need to do something different?

Cheers
Alex
 
Old 03-29-2017, 10:34 AM   #10
Sefyir
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Quote:
Originally Posted by slayer_1994 View Post
Hi Guys

Thanks for all your help on this much appreciated

Usually for time you take the first 10 characters of a files name, what if the file I am looking at has the date within it?
File 'Wynyard_MTP_Primary-btstats-2017-03-29-10:34:50.xml'

This is the file I want to do the same the difference between the dates but as it has the date already in it won't I need to do something different?

Cheers
Alex
Now you're looking to match a string.
That can be done with grep and regular expressions. Character Classes and Bracket Expressions may help you here (look in man grep)

For example, to match 4 digits, followed by a dash, then 2 digits I would do something like:

Code:
$ echo 'hello 5555-33 world' | grep -oE [[:digit:]]{4}-[[:digit:]]{2}
5555-33
Code:
       -E, --extended-regexp
              Interpret PATTERN as an extended regular  expression  (ERE,  see
              below).

       -o, --only-matching
              Print  only  the  matched  (non-empty) parts of a matching line,
              with each such part on a separate output line.
 
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