verbose Flag Prints to stderr, not stdout

[jdnordy]

Bug:

When running geoipudate -v, I noticed that it prints to stderr instead of stdout. I ran into this issue when trying to print output to a log file.

Example 1:
geoipupdate -v 1>/var/www/test.txt

terminal:

Using config file /usr/local/etc/GeoIP.conf
Using database directory {DATABASE_DIR}
Performing get filename request to https://updates.maxmind.com/app/update_getfilename?product_id=GeoLite2-City
Acquired lock file lock ({FILE_PATH}/.geoipupdate.lock)
Calculated MD5 sum for {FILE_PATH}/GeoLite2-City.mmdb: d90975ccfa5460d7ee2b2a9a4ebd93ae
Performing update request to https://updates.maxmind.com/geoip/databases/GeoLite2-City/update?db_md5=d90975ccfa5460d7ee2b2a9a4ebd93ae
No new updates available for GeoLite2-City

test.txt:

// empty

Example 2:
geoipupdate -v 2>/var/www/test.txt

terminal:

// empty

test.txt

Using config file /usr/local/etc/GeoIP.conf
Using database directory {DATABASE_DIR}
Performing get filename request to https://updates.maxmind.com/app/update_getfilename?product_id=GeoLite2-City
Acquired lock file lock ({FILE_PATH}/.geoipupdate.lock)
Calculated MD5 sum for {FILE_PATH}/GeoLite2-City.mmdb: d90975ccfa5460d7ee2b2a9a4ebd93ae
Performing update request to https://updates.maxmind.com/geoip/databases/GeoLite2-City/update?db_md5=d90975ccfa5460d7ee2b2a9a4ebd93ae
No new updates available for GeoLite2-City

Possible Solution:

Instead of of using log.Printf() for verbose flag output, use fmt.Printf()

[horgh]

I agree it can be unexpected, but I don't know that it's necessarily a bug or necessary to change. stderr is often used this way, e.g. see its description on https://pubs.opengroup.org/onlinepubs/9699919799/functions/stdin.html ("standard error (for writing diagnostic output)").

[dmitrisky]

Vote for using stdout for such messages too - it is just additional information, not errors IMO. As for me, it breaks automation (e.g. ansible playbooks) logic, - it's just weird to check stderr if new update was received or not.