Unix Shell - date function current month and last month the same

Author

date function current month and last month the same

wolffc@gmail.com

2007-05-31, 1:21 pm

I have a process the uses the date function to get the last month and
the current month. Here are the functions

set x = `date -d "-1 month" +%b`
set y = `date -d "0 month" +%b`

For some reason x and y are both May. Does this have something to do
with May being 31 days? This had been working all of April and all of
May. I am using csh

Thanks for any help

Stephane CHAZELAS

2007-05-31, 1:21 pm

2007-05-31, 08:28(-07), wolffc@gmail.com:
> I have a process the uses the date function to get the last month and
> the current month. Here are the functions
>
> set x = `date -d "-1 month" +%b`
> set y = `date -d "0 month" +%b`
>
> For some reason x and y are both May. Does this have something to do
> with May being 31 days? This had been working all of April and all of
> May. I am using csh
[...]

Yes, that's probably the reason.

You can do (sh syntax):

LC_ALL=C date +%bDecJanFebMarAprMayJunJulAugSepOctNovD
ec |
sed 's/$...$.*$...$\1.*/\2/'

I'd recommend not to use csh for scripting.

--
Stéphane

Bill Marcum

2007-05-31, 1:21 pm

On 31 May 2007 08:28:26 -0700, wolffc@gmail.com
<wolffc@gmail.com> wrote:
>
>
> I have a process the uses the date function to get the last month and
> the current month. Here are the functions
>
> set x = `date -d "-1 month" +%b`
> set y = `date -d "0 month" +%b`
>
> For some reason x and y are both May. Does this have something to do
> with May being 31 days? This had been working all of April and all of
> May. I am using csh
>
From `info date`:
The fuzz in units can cause problems with relative items. For
example, `2003-07-31 -1 month' might evaluate to 2003-07-01, because
2003-06-31 is an invalid date. To determine the previous month more
reliably, you can ask for the month before the 15th of the current
month. For example:

$ date -R
Thu, 31 Jul 2003 13:02:39 -0700
$ date --date='-1 month' +'Last month was %B?'
Last month was July?
$ date --date="$(date +%Y-%m-15) -1 month" +'Last month was %B!'
Last month was June!

--
Most people prefer certainty to truth.

Jose H.

2007-05-31, 7:24 pm

I think this is easier:

date -d "`date +%_d` day" +%b

Regards.

2007-05-31, 08:28(-07), wol...@gmail.com:> I have a process the uses
the date function to get the last month and
> the current month. Here are the functions

> set x = `date -d "-1 month" +%b`
> set y = `date -d "0 month" +%b`

> For some reason x and y are both May. Does this have something to
do
> with May being 31 days? This had been working all of April and all
of
> May. I am using csh