Pipe or Redirect within Java Command

it's common knowledge to use Runtime.getRuntime().exec(command) to execute any Unix command or Windows command in a Java application. However, when you try to include the pipe '|' or  redirect '>' in the command to alter any output pattern, most of the time the Java will not interpret your command as expected which will turn out to be an error finally. For example, when I tried to run ffmpeg command to encode any video and would like to capture those outputs into a log file, an error of "Unable to find a suitable output format for '>'" will appear.

In order to make Java "understand" out purpose, you cannot directly insert the usual command into the exec() parameter. There is a workaround which will solve the issue.

Construct an array:

String[] commands = {
"/bin/sh",
"-c",
YOUR REAL COMMAND HERE
}

and pass the commands as argument to the Runtime.getRuntime().exec(commands). In this way, the Java environment will make a sh (YOU COULD USE BASH) environment to execute your command, which will take the pipe and redirect into consideration.

Redirect vs Forward

In the context of web programming, a lot of ambiguity existed between Redirect and Forward. Here is a short summary of the differences between these two terms.

1) Forward can only be direct to an internal page, however Redirect can be used both to an internal page and external page.

2) Forward is much faster than Redirect

3) With Forward the browser is unaware of what happens, and the URL address remains the original link, while Redirect will initiate a new request that the browser will update its address to the new link.

4) As a result of the browser awareness, the refresh function will be failed in the Forward since the URL has not changed, but the Redirect will be all the same.

5) Still with the same reason, with those operations have side-effect, say update the status of database, a Redirect should be used to avoid the refresh Forward to generate any duplicate operations.