mongo copy from one collection to another (on the same db)

Question

I have got mongo db called test and in this db two collections collection1 and collection1_backup. How to replace content of col

Answer 1

also usefull: to export collection to json file

mongoexport --collection collection1_backup --out collection1.json

to import collection from json file

mongoimport --db test --collection collection1 --file collection1.json

to import single collection from backup/dump file one need to convert *.bson file to *.json by using

bsondump collection1_backup.bson > collection1_backup.json