Leading Zero when extract Day and Month - postgresql

Question

Hello i'm trying to extract current day and month in a query. This query is filling table from csv file.
the file is named like this:
LOG_01_01_2018.csv
My query search for file:
LOG_1_1_2018.csv
With no Zero in front day and month. How to add Zero numbers?
Here is the code:
execute format ($f$COPY tmp_x FROM 'D:\Programs\PS\download_files_from_ftp_avtomat\files\LOG_%s_%s_%s.csv'
(header, FORMAT CSV, DELIMITER ',', NULL ' ', ENCODING 'WIN1251');
$f$,extract(day from now()),extract(month from now()),extract(year from now()));

Answer 1

One option uses LPAD:
execute format ($f$COPY tmp_x FROM 'D:\Programs\PS\download_files_from_ftp_avtomat\files\LOG_%s_%s_%s.csv'
(header, FORMAT CSV, DELIMITER ',', NULL ' ', ENCODING 'WIN1251');
$f$,
lpad(extract(day from now())::text, 2, '0'),
lpad(extract(month from now())::text, 2, '0'),
extract(year from now()));
The year would always be a fixed width four digit number, unless you plan to work with data which existed before computers were around.

Answer 2

https://www.postgresql.org/docs/current/static/functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT
extract(field from timestamp) returns double precision, so you either lpad zero to it (making the value text), or just use to_char with data mask, eg:
t=# select extract(day from now()), to_char(now(),'MM'),extract(year from now());
date_part | to_char | date_part
-----------+---------+-----------
19 | 01 | 2018
(1 row)

Answer 3

Looks shorter to use to_char():
SELECT to_char(now(),'DD')||'/'||to_char(now(),'MM')||'/'||to_char(now(),'YYYY')