How to use a pipe with lftp?

I have files ending with apk in my desktop pc's terminal: ls | grep apk DroidEdit_v1.23.6.apk I connect to my android phone with lftp from my desktop pc: lftp 192.168.31.130:3721 lftp 192.168.31.130:~> lcd Downloads lcd ok, local cwd=/home/debian/Downloads lftp 192.168.31.130:~> !ls DroidEdit_v1.23.6.apk Why can't the pipe be used in an lftp command? lftp 192.168.31.130:/> !ls | !grep apk bash: line 1: !grep: command not found