How to use linux commands involving ">" through runTime.exec()

Question

I'm new to Java. I want to use a command

"ps -e > /home/root/workspace/MyProject/ProcessList.txt"

with runTime.exec();

On searching through the web, I came to know that runTime.exec() doesn't support pipes or redirecting. Please let me know how can I execute this command with my Java code. Please give exact answers.

kmkaplan · Accepted Answer · 2012-12-02T18:19:27.900

1

Pipes and redirection are features provided by the shell. The easy (and dirty) solution is to spawn the command inside a shell: "/bin/sh -c 'ps -e > /home/root/workspace/MyProject/ProcessList.txt'".

Edit: I had forgotten that the default StringTokenizer does not work with quoted strings. Provide arguments as an array of strings.

String[] args = {
    "/bin/sh",
    "-c",
    "ps -e > /home/root/workspace/MyProject/ProcessList.txt"
};
java.lang.Runtime.getRuntime(args);

edited Dec 02 '12 at 18:19

answered Dec 02 '12 at 16:35

kmkaplan

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4
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so you're saying it should be something like: run.exec("/bin/sh -c 'ps -e > /home/root/workspace/MyProject/ProcessList.txt'"); ???? – Ingila Ejaz Dec 02 '12 at 17:57
@IngilaEjaz Exactly. Edited to clarify. – kmkaplan Dec 02 '12 at 18:12
@IngilaEjaz You have access rights to create the file? The directory `/home/root/workspace/MyProject` already exists? – kmkaplan Dec 02 '12 at 18:17
@IngilaEjaz I had forgotten that the default StringTokenizer does not work with quoted strings. See my edit. – kmkaplan Dec 02 '12 at 18:24
I did exactly what you wrote. Still no luck :'( it says no such file :( – Ingila Ejaz Dec 02 '12 at 18:55
@IngilaEjaz it means you have to create the `/home/root/workspace/MyProject`directory first. – kmkaplan Dec 02 '12 at 18:59
It is already created MyProject is where I have that run.exec() method defined :( – Ingila Ejaz Dec 02 '12 at 19:31
Thanks so much kmkaplan :) I had been trying to do it for like 2 days :) – Ingila Ejaz Dec 02 '12 at 19:36

score 0 · Answer 2 · edited May 23 '17 at 12:04

0

You could take a look at this question: Input and Output Stream Pipe in Java

Otherwise, if you know you are on a platform that supports the bourne shell (sh), you could add that to the command to run the original command in that shell:

"sh -c 'ps -e > /home/root/workspace/MyProject/ProcessList.txt'"

edited May 23 '17 at 12:04

Community

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1

answered Dec 02 '12 at 16:36

Victor Zamanian

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How to use linux commands involving ">" through runTime.exec()

2 Answers2