Script to copy files for last month - windows

Question

I am trying to copy files using robocopy. The files I want to copy should be of last month(not one month old) i.e. on if I am running the script in the march month(any day) then it should copy all the files with timestamp of february. I am using below script:
robocopy source/*.prev destination maxage:20180201 minage:20180228
How to use the date as a variable here so I don't have to manually change it every month?

Answer 1

Having GNU date around you can do it this way:
start=$(date -d "$(date +%Y-%m-1) -1 month" +%Y%m%d)
end=(date -d "$(date +%Y-%m-1) -1 day" +%Y%m%d)
robocopy source/*.prev destination maxage:${start} minage:${end}
See linux - Using date command to get previous, current and next month
to see why we need -d. On 31st of a month the -1 month breaks otherwise.

Answer 2

The last date you can calculate like this: date -d "-$(date +%d) days -0 month" +%Y-%m-%d
which today outputs: 2018-02-28
The first date is a simple fixed start day: date -d "-$(date +%d) days -0 month" +%Y-%m-01
Which gaves when executed today: 2018-02-01
Your command could thus be:
robocopy source/*.prev destination \
maxage:$(date -d "-$(date +%d) days -0 month" +%Y%m01) \
minage:$(date -d "-$(date +%d) days -0 month" +%Y%m%d)
Edit: Since this is using GNU date syntax, this might not work on unix as stated by #ghoti

Answer 3

Let me assume POSIX compliant date is available.
Then how about:
#!/bin/bash
days[1]=31; days[2]=28; days[3]=31; days[4]=30
days[5]=31; days[6]=30; days[7]=31; days[8]=31
days[9]=30; days[10]=31; days[11]=30; days[12]=31
# current year and month
year=$(date +%Y)
month=$(( $(date +%m) + 0 ))
# previous month
if [[ "$month" = "1" ]]; then
year=$(( $year - 1 ))
month="12"
else
month=$(( $month - 1 ))
fi
days=${days[$month]}
# a leap year correction
if [[ "$month" = "2" ]]; then
days=$(( $days + ($year % 400 == 0 || ($year % 100 != 0 && $year % 4 == 0)) ))
fi
maxage=$( printf "%04d%02d%02d" $year $month 1 )
minage=$( printf "%04d%02d%02d" $year $month $days )

Answer 4

#echo off
setlocal enableextensions disabledelayedexpansion
rem Initialize variables to hold the previous month information
set "yyyy="
set "mm="
set "dd="
rem The robocopy in the for command will generate an error with the current date
for /f "tokens=1,2 delims=/" %%a in ('
robocopy "|" . /njh
') do if not defined yyyy (
rem Calculate previous month from current date
set /a "mm=(1%%b-90) %% 12 + 1", "yyyy=%%a - !(mm %% 12)"
rem Calculate the last day of the previous month
set /a "dd=30+((mm+mm/8) %% 2)+(-2+!(yyyy%%4)-!(yyyy%%100)+!(yyyy%%400))*!(%%b-3)"
rem Increase month and day for proper padding
set /a "dd+=100", "mm+=100"
)
rem Leave only the two right digits in month and day
set "mm=%mm:~-2%"
set "dd=%dd:~-2%"
rem Do the copy operation, selecting files from first to last days in previous month
robocopy "x:\source" "y:\target" *.prev /maxage:%yyyy%%mm%01 /minage:%yyyy%%mm%%dd%