Hi,

I'm trying to execute Linux Shell command from java application and get a runtime error after executing the above line:

Exception in thread "main" java.io.IOException: Cannot run program "cd": java.io.IOException: error=2, No such file or directory
at java.lang.ProcessBuilder.start(ProcessBuilder.java:459)
at java.lang.Runtime.exec(Runtime.java:593)
at java.lang.Runtime.exec(Runtime.java:431)
at java.lang.Runtime.exec(Runtime.java:328)
at App.main(App.java:137)
Caused by: java.io.IOException: java.io.IOException: error=2, No such file or directory
at java.lang.UNIXProcess.<init>(UNIXProcess.java:148)
at java.lang.ProcessImpl.start(ProcessImpl.java:65)
at java.lang.ProcessBuilder.start(ProcessBuilder.java:452)
... 4 more

It works for other commands like "pwd", "ls -l" etc. but not "cd".

Any idea why?

thanks in advance,
tatarin

guess: 'cd' is a built-in shell command, and getRuntime is expecting an actual program?

If it does not understand "cd" what would be the alternative to set a working directory to say "usr/local/username"?

You can string a path together using System.getProperty(some_dir).

For example,

File file = new File(System.getProperty("user.home")); //we start from the user's home dir
File parentFile = file.getParentFile().getParentFile(); //climb up two levels i.e. all the way up to /
if (parentFile.getAbsolutePath().equals("/")){ // check whether we really have /
String [] files = parentFile.list(); //list the contents ...
for (String s : files) //and print them out
System.out.println(s);
}

This will list all the files directly under /.

You can then move from / to /usr/local with:
File usrLocal = new File(parentFile + "usr" + File.separator + "local")

or all in one go, like this, much shorter:
String path = "/usr/local";
File usrLocal = new File(path);
String [] usrLocalFiles = usrLocal.list();
for (String s : usrLocalFiles)
System.out.println(s);