[Hadoop Wiki] Update of "BindException" by SteveLoughran

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The "BindException" page has been changed by SteveLoughran:
https://wiki.apache.org/hadoop/BindException?action=diff&rev1=5&rev2=6

Comment:
Because some people don't know what to do once they have that port/process

   * The port is in use (likeliest)
   * If the port number is below 1024, the OS may be preventing your program from binding to a "trusted port"
   * If the configuration is a {{{hostname:port}}} value, it may be that the hostname is wrong -or its IP address isn't one your machine has.
+  * There is an instance of the service already running.
  
  If the port is "0", then the OS is looking for any free port -so the port-in-use and port-below-1024 problems are highly unlikely to be the cause of the problem.
  
+ As you cannot have more than one process listening on a TCP port, whatever is listening is stopping the service coming up. You will need to track down and stop that process, or change the service you are trying to start up to listen to a different port.
+ 
  How to track down the problem
   1. identify which port the program is trying to bind to
-  1. as root use {{{netstat -a -t --numeric-ports -p}}} to list the ports that are in use by number and process. (On OS/X you need to use {{{lsof}}})
   1. identify the port that is in use and the program that is in use
+  1. as root use {{{netstat -a -t --numeric-ports -p}}} to list the ports that are in use by number and process. (On OS/X you need to use {{{lsof}}}).
   1. Make sure the hostname is valid:try to ping it; use {{{ifconfig}}} to list the network interfaces and their IP addresses.
   1. try and identify why it is in use. {{{telnet <hostname> <port>}}} and pointing a web browser at it are both good tricks.
   1. change the configuration of one of the programs to listen on a different port.