This command restores a key previously backed up with the export command.
If the --paper option is given, the import will be an interactive process in which each line is checked
for plausibility before proceeding to the next line. For this format PATH must not be given.
For repositories using keyfile encryption, the key file which borgkeyimport writes to depends on
several factors. If the BORG_KEY_FILE environment variable is set and non-empty, borgkeyimport creates
or overwrites that file named by $BORG_KEY_FILE. Otherwise, borgkeyimport searches in the
$BORG_KEYS_DIR directory for a key file associated with the repository. If a key file is found in
$BORG_KEYS_DIR, borgkeyimport overwrites it; otherwise, borgkeyimport creates a new key file in
$BORG_KEYS_DIR.