Local time to GMT time

Shell Programming and Scripting
1

Gents,

Please can help with this.

the column in red is the local time
the column in blue is the GPStime

4153152529951 2/12/17	12:00:04.980	951	2960	41531.0	52529.0	1170882022980002
4108153261942 2/12/17	12:00:07.944	942	2959	41081.0	53261.0	1170882025944002
41511523611660 2/12/17	1:55:32.180	1660	2959	41511.0	52361.0	1170888950180002
410675237398 2/12/17	7:36:48.980	98	2958	41067.0	52373.0	1170909426980002

I would like to get the time -3hrs in GMT time.

Example

4153152529951 2/11/17	21:00:04.980	951	2960	41531.0	52529.0	1170882022980002
4108153261942 2/11/17	21:00:07.944	942	2959	41081.0	53261.0	1170882025944002
41511523611660 2/11/17	22:55:32.180	1660	2959	41511.0	52361.0	1170888950180002
410675237398 2/12/17	04:36:48.980	98	2958	41067.0	52373.0	1170909426980002

Please advise. Thanks for your help

2

By 'column' I think you mean 'row'.

What's your system? Date math is tricky without GNU date.

3

Dear Corona688
sorry there was a error in the color, it is column, :slight_smile:
i am using debian 7. i try to do it manually (hr-3) but i belive it can be done automatically, maybe using the GPStime?

4

But ... that column doesn't change.

And the row you highlighted before still changes.

What does 1170882025944002 represent, anyway?

5

something to start with to see the conversion ONLY:
awk -f jiam.awk myInputFile where jiam.awk is:

{
  d=$2
  t=$3
  split(d,dA,"/")
  split(t,tA,"[:.]")

  dateSpec=sprintf("20%02d %02d %02d %02d %02d %02d", dA[3], dA[1], dA[3], tA[1], tA[2], tA[3])

  time=mktime(dateSpec)

  utc=strftime("%m/%d/%Y %H:%M:%S." tA[4], time, 1)

  printf("dateSpec->[%s] utc->[%s]\n", dateSpec, utc)
}
6

Mayhap sth. along this line:

awk -vGPS0=$(TZ=UTC date -d'1/6/1980 0:00' +%s) '{print "@" int($NF/1E6)+GPS0}' CONVFMT="%.f" file | LC_ALL=C TZ=+3 date -f-
Sat Feb 11 21:00:23  2017
Sat Feb 11 21:00:26  2017
Sat Feb 11 22:55:50  2017
Sun Feb 12 04:37:07  2017

That's the GPS date / time representation, starting at 6. Jan 1980, 0:00h UTC, in microseconds. Delta to *nix epoch is 315964800 sec.

7

jiam912, you seem to work with gpstime in your data files a fair bit. perhaps you would benefit from this GNU awk function strfgps() which operates like the strftime() function except with gpstime:

TZ=0 gawk '
function strfgps(fmt, gps) {
    gsub(/%f/, sprintf("%03d", gps % 1E6 / 1E3), fmt)
    return strftime(fmt, gps / 1E6 + 315964800)
}
{
  $2 = strfgps("%m/%d/%y", $NF)
  $3 = strfgps("%H:%M:%S.%f", $NF)
  print
}' OFS="\t" infile

I used gsub() to add support for the %f format => milliseconds as 3 digit number.

output:

4153152529951   02/11/17        21:00:22.980    951     2960    41531.0 52529.0 1170882022980002
4108153261942   02/11/17        21:00:25.944    942     2959    41081.0 53261.0 1170882025944002
41511523611660  02/11/17        22:55:50.180    1660    2959    41511.0 52361.0 1170888950180002
410675237398    02/12/17        04:37:06.980    98      2958    41067.0 52373.0 1170909426980002
8

Dear Xl and all

thanks a lot

---------- Post updated at 05:48 AM ---------- Previous update was at 12:38 AM ----------

Dear Xl

I have added

    return strftime(fmt, gps / 1E6 + 315964800 - 18)

To get exactly the time -3hs