running unix script from java app

[sight]

String[] cmd = {"/bin/sh", "-c", "ls > hello"};
Runtime.getRuntime().exec(cmd);
Following code doesn't create a file hello when app is run on unix?!??How
can i start unix script from java app?I'm using cygwin instead of Unix

 

[Oliver Wong]

String[] cmd = {"/bin/sh", "-c", "ls > hello"};
Runtime.getRuntime().exec(cmd);
Following code doesn't create a file hello when app is run on unix?!??How
can i start unix script from java app?I'm using cygwin instead of Unix

Did you try:

String[] cmd = {"/bin/sh", "-c", "ls" "> hello"};

or

String[] cmd = {"/bin/sh", "-c", "ls" ">" "hello"};

or other variants? I believe it's the shell and not the ls program, which
takes care of redirecting output.

- Oliver

 

[=?ISO-8859-2?Q?Dra=BEen_Gemi=E6?=]

String[] cmd = {"/bin/sh", "-c", "ls > hello"};
Runtime.getRuntime().exec(cmd);
Following code doesn't create a file hello when app is run on unix?!??How
can i start unix script from java app?I'm using cygwin instead of Unix

I think that the problem is with "ls > hello" part. Runtime.exec()
method creates a Process object instance. Java captures stdin,
stdout and stderr streams, so you are not able to redirect. The
command is probably executed, but you are not able to see the result.

Check the java.lang.Process documentation.

DG

 

[Chris Uppal]

String[] cmd = {"/bin/sh", "-c", "ls > hello"};
Runtime.getRuntime().exec(cmd);
Following code doesn't create a file hello when app is run on unix?!??How
can i start unix script from java app?I'm using cygwin instead of Unix

Your approach would, I think, be correct on Unix. You are passing the right
string to the shell to be interpreted as a command. I suspect the problem is
with Cygwin, or more accurately, with the fact that Java doesn't know about
Cygwin. So the first parameter:
"/bin/sh"
with attempt to find
.\bin\sh.exe
in a subdirectory of whatever "current directory" the Windows process thinks it
is in. You may get better results with:
"C:/cygwin/bin/sh"
(replacing the actual path according to where you have actually installed
Cygwin).

-- chris

 

[=?ISO-8859-2?Q?Dra=BEen_Gemi=E6?=]

or other variants? I believe it's the shell and not the ls program,
which takes care of redirecting output.

That is, in fact, correct. In UNIX, child process, by default, inherits
parents file descriptors. That means that paren program arranges the
descriptors before forking child process.

Check dup, dup2, open and close system calls.

DG