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(java.lang.Runtime()).exec(new String[]) ...

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  (java.lang.Runtime()).exec(new String[]) ...  lbrt chx _ gemale - 2011-12-10 06:01 +0000
    Re: (java.lang.Runtime()).exec(new String[]) ... Lew <lewbloch@gmail.com> - 2011-12-09 23:00 -0800
    Re: (java.lang.Runtime()).exec(new String[]) ... Roedy Green <see_website@mindprod.com.invalid> - 2011-12-10 02:44 -0800
    Re: (java.lang.Runtime()).exec(new String[]) ... Nigel Wade <nmw-news@ion.le.ac.uk> - 2011-12-12 14:31 +0000

#10639 — (java.lang.Runtime()).exec(new String[]) ...

 Something like this: 
~ 
 Process proc = (java.lang.Runtime()).exec((new String[]{"ls", "-l", "/media/sda1/Physical_Basis.flv"}));
~ 
 works just fine.
~ 
 Why doesn't something like,  say:
~ 
 Process proc = (java.lang.Runtime()).exec((new String[]{"date;", "time","ls", "-l", "/media/sda1/Physical_Basis.flv;", "date;"}));
~ 
 work?
~ 
 lbrtchx
 comp.lang.java.programmer

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#10641

(unknown) wrote:
> Something like this: 

Not too very like, I think - 

>  Process proc = (java.lang.Runtime()).exec((new String[]{"ls", "-l", "/media/sda1/Physical_Basis.flv"}));
> ~ 
>  works just fine.

except that it won't compile, as Stefan hinted.

>  Why doesn't something like,  say:
> ~ 
>  Process proc = (java.lang.Runtime()).exec((new String[]{"date;", "time","ls", "-l", "/media/sda1/Physical_Basis.flv;", "date;"}));
> ~ 
>  work?

For starters, for the same reason the other one doesn't.

Please reply with a copy-and-paste of the output from 'javac' on these idioms, placed into an SSCCE, of course. 

A minor point unrelated to your major question - you never have to specify 'java.lang' for the types in that package.  Just 'Runtime' will do nicely, thank you.

<http://docs.oracle.com/javase/7/docs/api/java/lang/Runtime.html>

-- 
Lew

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#10642

On 10 Dec 2011 06:01:03 GMT, lbrt chx _ gemale wrote, quoted or
indirectly quoted someone who said :

>~ 
> Why doesn't something like,  say:
>~ 
> Process proc = (java.lang.Runtime()).exec((new String[]{"date;", "time","ls", "-l", "/media/sda1/Physical_Basis.flv;", "date;"}));
 
because date and time are not programs, but elements of a script that
requires a commend interpreter program.

See http://mindprod.com/jgloss/exec.html
for how to spawn a command interpreter.
-- 
Roedy Green Canadian Mind Products
http://mindprod.com
For me, the appeal of computer programming is that
even though I am quite a klutz,
I can still produce something, in a sense
perfect, because the computer gives me as many
chances as I please to get it right.
 

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#10667

On 10/12/11 06:01, lbrt chx _ gemale wrote:
>   Something like this:
> ~
>   Process proc = (java.lang.Runtime()).exec((new String[]{"ls", "-l", "/media/sda1/Physical_Basis.flv"}));
> ~
>   works just fine.
> ~
>   Why doesn't something like,  say:
> ~
>   Process proc = (java.lang.Runtime()).exec((new String[]{"date;", "time","ls", "-l", "/media/sda1/Physical_Basis.flv;", "date;"}));
> ~
>   work?
> ~

Besides the other problems, even if the code were executable it would 
fail because you are attempting to run a sequence of commands.

Process.exec() runs one command, the first argument. The rest of the 
string elements are arguments to that command. It will not run a 
sequence of commands as implied by the ";" ending each of the first two 
commands. That requires you to use a shell to interpret the command 
sequence.

-- 
Nigel Wade

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