java Runtime.exec to run shell script - cannot open file

Question

I am using Runtime.getRuntime().exec() to run a shell script from java code.

    String[] cmd = {"sh",  "build.sh", "/Path/to my/sh file"};
    try{
        Process proc = Runtime.getRuntime().exec( cmd );
    }
    catch(Exception e){
        System.out.println("Exception is:"+e);
    }

It gives me the following output in console:

sh: Can't open build.sh

Am I following some wrong approach here? Cannot make out why his happens.

EDIT

Based on the comment here, I have modified the String[] cmd = {"sh", "build.sh", "/Path/to my/sh file"}; to String[] cmd = {"sh", "/Path/to my/sh file/build.sh", "/Path/to my/sh file"}; . Now the problem is this script need to be executed from a particular path. When I execute this script from command prompt, I first change the directory to that path and execute it. How should I modify this code?

provide full path of build.sh i.e. path relative to the project folder — voidMainReturn
– voidMainReturn, Commented Jun 17, 2013 at 7:44
Read (and implement) all the recommendations of When Runtime.exec() won't. That might solve the problem. If not, it should provide more information as to the reason it failed. Then ignore that it refers to exec and build the Process using a ProcessBuilder. Also break a String arg into String[] args to account for arguments which themselves contain spaces. — Andrew Thompson
– Andrew Thompson, Commented Jun 17, 2013 at 7:55

fge · Accepted Answer · 2013-06-17 08:03:19Z

4

Use a ProcessBuilder and set the working directory of the process to the directory where your script actually is:

final ProcessBuilder pb = new ProcessBuilder("/bin/sh", "script.sh", "whatever",
    "arguments", "go", "here");
pb.directory(new File("/path/to/directory"));
// redirect stdout, stderr, etc
final Process p = pb.start();

See the ProcessBuilder javadoc. It contains an example of what you can do. Runtime.exec() is passé :p

answered Jun 17, 2013 at 8:03

fge

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1 Comment

fge Over a year ago

You're welcome! Learn this class, it is what you MUST use when running programs in Java.

Adam Siemion · Accepted Answer · 2013-06-17 07:43:09Z

1

sh is unable to find the build.sh script. To fix this you can provide the full path to build.sh.

answered Jun 17, 2013 at 7:43

Adam Siemion

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Comments

Stephen C · Accepted Answer · 2013-06-17 08:14:40Z

1

The problem is that the "sh" command is unable to resolving the relative path "build.sh" to an absolute path. The most likely explanation is that "build.sh" is not in the current directory when you launch the command.

Assuming that "/Path/to my/sh file" string is the path to the "build.sh" file, you need to run it like this:

String[] cmd = {"/bin/sh",  "/Path/to my/sh file/build.sh"};
try {
    Process proc = Runtime.getRuntime().exec(cmd);
    ...

(.... or the equivalent using ProcessBuilder)

On the other hand, if the "/Path/to my/sh file" string is supposed to be an argument to the "build.sh" script, then you need to run it like this:

String[] cmd = {"/bin/sh", "/some/dir/build.sh", "/Path/to my/sh file"};
try {
    Process proc = Runtime.getRuntime().exec(cmd);

@fge's answer gives an alternative approach. He is setting the current directory for the child process before it is launched. That is the correct solution for your updated Question.

edited Jun 17, 2013 at 8:14

answered Jun 17, 2013 at 8:09

Stephen C

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3 Comments

user1400538 Over a year ago

String[] cmd = {"/bin/sh", "/home/sreekumar/bin/build.sh"}; works. What if I need to execute this from a particular path. Similar to we change directory in terminal first and then execute the script?

Stephen C Over a year ago

@user1400538 - As I said, fge's Answer address your updated Question. Read it.

user1400538 Over a year ago

ok, done and it works, sorry I read the last part of your question later only. thanks.

Juned Ahsan · Accepted Answer · 2013-06-17 08:45:48Z

1

Try this:

 String[] cmd = {"sh build.sh", "/Path/to my/shfile"};

and better to use ProcessBuilder

ProcessBuilder pb = new ProcessBuilder("sh build.sh", "/Path/to my/shfile");

edited Jun 17, 2013 at 8:45

answered Jun 17, 2013 at 7:46

Juned Ahsan

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1 Comment

Stephen C Over a year ago

This won't help. You are telling the OS to run an executable with the pathname /bin/sh build.sh ... which definitely does NOT exist on any sane UNIX / Linux system.

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