I've never used Runtime.exec() but from prior discussions here I vaguely
recall that you need to feed it the name of a native executable. In your
case, the name of a shell should be the first thing you give to exec().

The API docs and/or Google Groups may well be your friends.

If you really are using echo to append to a file, I suggest you use Java
IO classes instead.

The main problem is that you are using shell features (redirection)
but Runtime.exec() does not invoke a shell.

To RGB: Although echo is built into many shells it's also a real
executable on Unix, so that isn't the reason a shell is necessary
here.

There may be additional problems with your *real* command if you are
using quotation marks to group arguments, since the command line is
tokenized without regard to quoting or escaping when you use
exec(String). A better choice is usually exec(String[]).

Try it like this:

 String[] cmd = { "/bin/sh", "-c", "echo 'tttt' >> /var/test/txt" };

/gordon

--

This subject was done to death last week (or was it the week before). Please
look through the Google groups archive for the comp.lang.java.* groups:

<http://groups.google.co.uk/groups?&as_epq=runtime.exec&as_ugroup=comp.lang.java.
*&as_drrb=b&as_mind=1&as_minm=12&as_miny=2007&as_maxd=13&as_maxm=12&as_maxy=2007>

On Thu, 13 Dec 2007 07:54:21 -0800 (PST), Mitschu
<michael.arnold@sisag.ch> wrote, quoted or indirectly quoted someone
who said :

See http://mindprod.com/jgloss/exec.html

You are making the most common error.  echo is not an executable.  It
is a command to the command interpreter, as is >>  (at least it is in
Windows, don't know about your platform).

You must spawn a copy of a command interpreter, and feed it that line
as a parameter.