no of days between two dates in yyyymmdd format

csegau · 09-18-2011, 12:21 PM

Hi All,

I have a file which has 3 column, column 2nd and 3rd have date in yyyymmdd format.

i have to find find the no. of days between two dates.

ex: file
column1 column2 column3
-----------------------------------
A 20090909 20100908
A 20080102 20090107
B 20110909 20110910
A 20001010 20030405

so i have to find out no of days when "A" was present.
this input "A" is command line argument, it can be "B" too..

-Thanks in advance

theNbomr · 09-18-2011, 02:15 PM

If I understand your question correctly, you want to calculate the difference between dates, in days, for records that match a specified argument. If so, this should be close:

Code:

#! /bin/bash
#
#   LQcsegau.sh
#      run as: LQcsegau.sh A    # (use record type as desired)
#      -  uses embedded data file name; customize as necessary
#
while read rec; do 
    #
    #  Split each record into separate fields
    #
    rectype=$(echo $rec | cut -d' ' -f1);
    d1=$(echo $rec | cut -d' ' -f2);
    d2=$(echo $rec | cut -d' ' -f3);
 
    #
    #   If record type matches that specified on commandline...
    #
    if [ "$rectype" = "$1" ]; then 
        #
        #   normalize dates to seconds-since-epoch
        #
        date1=$(date -d "$d1" "+%s" ); 
        date2=$(date -d "$d2" "+%s" );
        
        #
        #  Calculate difference in seconds, convert back to days, and report
        #
        days=$(( ($date2-$date1)/86400 )); 
        echo $days;
    fi; 
#
#  Read from data file
#
done < LQcsegau.dat

--- rod.