Logstash 1.5.1 not working in HP Unix

I am trying to use logstash 1.5.1 on a hp unix system, but I am getting the error no bash found.

But the older logstash runs fine on the same system with a problem of no cursor maintained for the log file due which I recieve duplicate logs on restart of logstash

Kindly guide me to solve this issue

Is the error something like bash command not found? That just means you should run ./bin/logstash depending on the directory you are in. Not sure I think I am still running logstash 1.5

Is logstash1.5 running without any issue?
Does logstash 1.5 maintain the cursor of the log file being read thus eliminating log duplication?