when using mongoexport -v, the additional logging is echoed to stdout. one typically assumes verbose logging will be sent to stderr, particularly when the data being exported is echoed to stdout.

to reproduce:
mongoexport -v -d mydb -c mycoll --csv | tee mycoll.txt

expected:
mycoll.txt contains only the header line and exported data

actual:
mycoll.txt contains -v output, header line and exported data