how to get the first and the last day in the month with "date" command

myhnet · 06-16-2009, 01:31 AM

I am using CentOS 5.3 and I knew that we can easily to use "-d" option to get some special day.
like to get yesterday

Code:

date -d "yesterday"

to get today in the pasted mont

Code:

date -d "last month"

but is there a shortcut to get the day of the first and the last day in a month.

like
2009-02-01 2009-05-01 2009-06-01 (first day)
2009-02-28 2009-05-31 2009-06-30 (last day)

thank you very much

colucix · 06-16-2009, 01:44 AM

As far as I know there is not a date specification for the last day of the month. To retrieve the last day of the current month I used the cal command:

Code:

echo $(cal) | awk '{print $NF}'

sonnik · 06-16-2009, 01:50 AM

Since you know the first day of the month is always the first, you can do the following if you'd like:

Code:

date -d "yesterday 2009-06-01"

Code:

date -d "2009-06-01"

The first line will provide "yesterday" relative to June 1.

myhnet · 06-16-2009, 02:15 AM

Quote:

Originally Posted by sonnik

Since you know the first day of the month is always the first, you can do the following if you'd like:

Code:

date -d "yesterday 2009-06-01"

Code:

date -d "2009-06-01"

The first line will provide "yesterday" relative to June 1.

but you can not specify the month, like how you get this month?

Quote:

Originally Posted by colucix

As far as I know there is not a date specification for the last day of the month. To retrieve the last day of the current month I used the cal command:

Code:

echo $(cal) | awk '{print $NF}'

seems a better choice but still complex.

colucix · 06-16-2009, 02:20 AM

Following the suggestion by sonnik, the following gives the last day of the month:

Code:

$ date -d "2009-06-01 yesterday 1 month"
Tue Jun 30 00:00:00 CEST 2009
$ date -d "2009-02-01 yesterday 1 month"
Sat Feb 28 00:00:00 CET 2009

myhnet · 06-16-2009, 02:31 AM

but you still have a static date, how about you even don't know 2009-06-01

ghostdog74 · 06-16-2009, 02:31 AM

Quote:

Originally Posted by colucix

Code:

echo $(cal) | awk '{print $NF}'

why the echo?

Code:

cal |awk 'NF{last=$NF}END{print last}'

colucix · 06-16-2009, 02:50 AM

Quote:

Originally Posted by myhnet

but you still have a static date, how about you even don't know 2009-06-01

Code:

date -d "$(date +%Y-%m)-01 yesterday 1 month"

myhnet · 06-16-2009, 02:56 AM

Quote:

Originally Posted by colucix

Code:

date -d "$(date +%Y-%m)-01 yesterday 1 month"

hmmm, maybe this is the way.
thank you for your patience.

ghostdog74 · 06-16-2009, 03:16 AM

make sure you test different combinations before implementing live. how to get the previous month's last day etc etc