$ pda set a1@ekf 1
$ pda set a2@ekf 2
$ pda set b1@ekf 3
$ pda export ekf --key "a*"
{"key":"a1","value":"1","encoding":"text"}
{"key":"a2","value":"2","encoding":"text"}
$ pda export ekf --key "c*" --> FAIL
FAIL  cannot ls '@ekf': no matches for key pattern 'c*'