How can i extarct the output from a file which has been updated from last half an hou

tarundeepdhawan · #1 (**permalink**) 06-18-2008

hi,
I have a log file , which is appending with current data
i need the extarct which is updated from last 30 minutes
the format of the date is Jun 18, 2008 8:59:18 AM
how can i subtract 30 mins from the current date
thanks
Tarun.

danmero · #2 (**permalink**) 06-18-2008

Search the forum for date & time calculation for your OS.

jim mcnamara · #3 (**permalink**) 06-18-2008

one way

Code:

#!/bin/ksh
# filetimes
minsago()
{
    perl  -e '
          use POSIX qw(strftime);
          $fmt="%c";  # change this to meet your needs
          $now=time;
          $now-=1800;  # 30 minutes = 1800 seconds
         ($sec,$min,$hour,$day,$mon,$yr,$wday,$yday,$dntcare)=localtime($now);
          $result=strftime($fmt, $sec,$min,$hour,$day,$mon,$yr,$wday,$yday,$dntcare);
          print "$result"
         ' $1
}
start=$(minsago)
echo "$start"

Change the $fmt = "%c" -- if your locale does not print the date in the correct format.

ripat · #4 (**permalink**) 06-18-2008

With gnu coreutils date:

Code:

DTE=$(date "+%b %d, %Y %r" --date "now -30 minutes")
grep "$DTE" your-file

If your locale don't use C:

Code:

LC_ALL=C DTE=$(date "+%b %d, %Y %r" --date "now -30 minutes")
grep "$DTE" your-file

tarundeepdhawan · #5 (**permalink**) 06-23-2008

Hi Ripat
Thanks for the reply, but it does not solve my purpose, it is just changing the format of the date but not subtracting 30 mins

$ DTE=$(date "+%b %d, %Y %r" --date "now -30 minutes")
$ echo $DTE
Jun 23, 2008 02:43:34 AM
$ date
Mon Jun 23 02:43:49 EDT 2008

i have a log file i need to extract data which has been updated from last 30 mins

plz advise

ripat · #6 (**permalink**) 06-23-2008

It works on my linux box with coreutil's date. Are you using GNU date? Which version?

Try:

Code:

$ date "+%b %d, %Y %r" --date "now 30 minutes ago"

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