My embedded system have a industrial computer,the industrial PC run a program automatically while it boot,because I had add a command line in the rc.local,the program can display its status in realtime.I can telnet to the industrial PC with root user,now is the question:When I telnet to the remote PC,How can I watch the process stdout which are running,or redirection the process stdout?
Thank you for any suggestion!

You could redirect the output to a file in /etc/rc.local and then just run tail -f on that file.

Thank you for your suggestion.I think if I redirection my program's stdout to a file,I can say it is a log file.the log file will increase its size continually,inIn the other hand my disk have not enough size,only 128M,I have used 120M,I don't want to maintain the log file.Is there a kind of file presently in the linux system which have fixed size and can be circularity structure,its head link to its tail.In the other word,it can be access like stdout,always record the last data,the new data cover the old data,the file size is fixed.

A 'named pipe' might be helpful. Look at the man page for mkfifo.