Under my project, I have a Java class file, inside of which I have a routine which executes the following external SFTP script file: #!/bin/sh echo "cd AV/OASIS" >> sftp echo "put $1 $2" >> sftp echo "get AV/OASIS/$2 $3$2" >> sftp echo "bye" >> sftp /usr/local/bin/sftp -b sftp id@domain cat /dev/null > sftp exit 0 The Java code which executes the script file is as below: String script = "full path of script"; Process p = Runtime.getRuntime().exec(script + " " + param1 + " " + param2 + " " + param3); However, I'm not sure why, but the log generated by the class file always shows the error "Host key verification failed. Connection closed." I'd isolated that line in the script which connected to the remote machine, and ran it on the local machine (where this class file and script file are stored), and the command executed successfully I'd manually run the command which the Java class file will execute and it also tested okay: $ script.sh param1 param2 param3 I'd tried to look up the error message on the Internet, and apparently it seems to have something to do with known_hosts. Could this be the reason, or is there something else I'm missing? Thanks so much!