Changing directory using exec

[festo]

I am wondering why I cannot change the directory using my java program
like so:

Runtime runtime = Runtime.getRuntime();
Process proc = runtime.exec("cd" + " " + directory);


Is there an easy way to accomplish this because using ("ls" + .....)
works but not the "cd".

Please help.

fezto

 

[Thomas Kellerer]

festo wrote on 25.10.2006 00:19:

I am wondering why I cannot change the directory using my java program
like so:

Runtime runtime = Runtime.getRuntime();
Process proc = runtime.exec("cd" + " " + directory);


Is there an easy way to accomplish this because using ("ls" + .....)
works but not the "cd".

You are starting a new process that will change *its* working directory. But
this will not change the working directory for the process that runs your Java
program.

But why do you want to do that?

Thomas

 

[Thomas Fritsch]

I am wondering why I cannot change the directory using my java program
like so:

Runtime runtime = Runtime.getRuntime();
Process proc = runtime.exec("cd" + " " + directory);


Is there an easy way to accomplish this because using ("ls" + .....)
works but not the "cd".

See the API doc of Runtime.
There are two exec() methods, which take a File parameter (the working
directory in which the process will run). Use for example:
Process proc = runtime.exec("ls" + ..., new String[0], new
File("/home/user"));

 

[festo]

I am doing a file transfer client server program and I need to be able
to change to a directory on the server to do an "ls" to list the
directory files then transfer file(s) from server to client.

I am wondering why I cannot change the directory using my java program
like so:

Runtime runtime = Runtime.getRuntime();
Process proc = runtime.exec("cd" + " " + directory);


Is there an easy way to accomplish this because using ("ls" + .....)
works but not the "cd".

See the API doc of Runtime.
There are two exec() methods, which take a File parameter (the working
directory in which the process will run). Use for example:
Process proc = runtime.exec("ls" + ..., new String[0], new
File("/home/user"));

 

[hiwa]

I am doing a file transfer client server program and I need to be able
to change to a directory on the server to do an "ls" to list the
directory files then transfer file(s) from server to client.

You don't need to change directory to do that -- listing files in a
directory and send one of them.

 

[Thomas Kellerer]

I am doing a file transfer client server program and I need to be able
to change to a directory on the server to do an "ls" to list the
directory files then transfer file(s) from server to client.

Why do you start a new process to list the files in a directory?

Have a look at File.listFile():

File dir = new File("/path/to/directory");
File[] filesInDir = dir.listFile();

Thomas

 

[Martin Gregorie]

I am doing a file transfer client server program and I need to be able
to change to a directory on the server to do an "ls" to list the
directory files then transfer file(s) from server to client.

Have you considered using a Java SSH client class to talk to a standard
ftpd or sshd server?

Java class libraries exist to implement the client end of an FTP
connection which would connect to a standard ftpd server and should do
everything you need, though its relatively insecure. See:
http://jakarta.apache.org/commons/net/api/org/apache/commons/net/ftp/FTPClient.html

If you need higher security, e.g. encrypted passwords and files in
transit you should look at SSH. A full SSH implementation supports the
scp facilities for file transfer as well as the sftp facilities which
are a close approximation to FTP in terms of directory listing, moving
around the directory tree and moving files to or from the server, but
encrypt files during transfer. See http://linuxmafia.com/ssh/java.html
for information on available class libraries.

Using either FTP or SSH will save you a shed load of work because the
servers are standard, tested off the shelf code and have been ported to
almost every OS capable of supporting them.