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Hello
I'm using java.lang.runtime.exec() in Windows enviroment without
problems. Now on a linux Server it won't run. Can you see an error?
Has the string to be terminated with sth? I tried \r and \n without
success.

try {
Runtime runtime = Runtime.getRuntime();
Process p = runtime.exec( "echo 'tttt' >> /var/test.txt" );
p.waitFor();
out.println("Exit status: " + p.exitValue() );
}catch(Exception e) {
out.println("Error: " + e );
}


Thanks for any help.
Michael

Mitschu wrote:
> Hello
> I'm using java.lang.runtime.exec() in Windows enviroment without
> problems. Now on a linux Server it won't run. Can you see an error?
> Has the string to be terminated with sth? I tried \r and \n without
> success.
>
> try {
> Runtime runtime = Runtime.getRuntime();
> Process p = runtime.exec( "echo 'tttt' >> /var/test.txt" );
> p.waitFor();
> out.println("Exit status: " + p.exitValue() );
> }catch(Exception e) {
> out.println("Error: " + e );
> }
>
>

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.

On Thu, 13 Dec 2007 07:54:21 -0800 (PST), Mitschu wrote:
> I'm using java.lang.runtime.exec() in Windows enviroment without
> problems. Now on a linux Server it won't run. Can you see an error?
> Has the string to be terminated with sth? I tried \r and \n without
> success.
>
> try {
> Runtime runtime = Runtime.getRuntime();
> Process p = runtime.exec( "echo 'tttt' >> /var/test.txt" );

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


--

Mitschu wrote:

> Hello
> I'm using java.lang.runtime.exec() in Windows enviroment without
> problems. Now on a linux Server it won't run. Can you see an error?
> Has the string to be terminated with sth? I tried \r and \n without
> success.
>
> try {
> Runtime runtime = Runtime.getRuntime();

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.ja va.*&as_drrb=b&as_mind=1&as_minm=12&as_miny=2007&a s_maxd=13&as_maxm=12&as_maxy=2007>

--
Nigel Wade, System Administrator, Space Plasma Physics Group,
University of Leicester, Leicester, LE1 7RH, UK
E-mail :
Phone : +44 (0)116 2523548, Fax : +44 (0)116 2523555

Nigel Wade schreef:
> Mitschu wrote:
>
>> Hello
>> I'm using java.lang.runtime.exec() in Windows enviroment without
>> problems. Now on a linux Server it won't run. Can you see an error?
>> Has the string to be terminated with sth? I tried \r and \n without
>> success.
>>
>> try {
>> Runtime runtime = Runtime.getRuntime();
>
> 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.ja va.*&as_drrb=b&as_mind=1&as_minm=12&as_miny=2007&a s_maxd=13&as_maxm=12&as_maxy=2007>

Indeed, and the thread was started by me.

In short:
- use ProcessBuilder instead of Runtime.exec (Java 5+)
- redirection will not work except if you invoke a shell and tell it to
run the command
- better read the output from the process and write it to a file
yourself, in a separate thread (watch out for the names of the methods)

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

Much luck, H.
--
Hendrik Maryns
http://tcl.sfs.uni-tuebingen.de/~hendrik/
==================
http://aouw.org
Ask smart questions, get good answers:
http://www.catb.org/~esr/faqs/smart-questions.html


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

> Process p = runtime.exec( "echo 'tttt' >> /var/test.txt" );

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.
--
Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

Roedy Green wrote:
> On Thu, 13 Dec 2007 07:54:21 -0800 (PST), Mitschu
> <> wrote, quoted or indirectly quoted someone
> who said :
>
>> Process p = runtime.exec( "echo 'tttt' >> /var/test.txt" );
>
> See http://mindprod.com/jgloss/exec.html
>
> You are making the most common error. echo is not an executable.

Probably one of the most common errors, but on my machine there is a
/bin/echo. There is also a build in echo in my shell (bash). Does that
mean I can both eat the cake and have it too?

//Roger Lindsjö