[SOLVED] How to return the system type in an SFTP?

Issue

FTP and SFTP are different, but I wanted to know is there a equivalent to a "SYST" command in FTP for SFTP. If I have an SFTP connection using JSch and I wanted to return the system type, how would I do that? I am converting FTP connection to SFTP. If there is no way to do with an SFTP, is there a workaround for it?

public String getSystemType()
        throws IOException, FtpException
{
    if(out == null)
        return null;
    acquire();    // Acquire the object

    try {
        ftpCommand("SYST");             //sends command to FTP to retrieve the system type.
        if(!reply.substring(0, 3).equals("215"))
            throw new FtpException(reply);
    } finally { 
        release();    // Release the object
    }

    return reply.substring(4);
}

I need this "system type" to parse the result of information of a file or directory from a location. It could be a Windows server or a UNIX server. Depending on that I need to parse it to retrieve

1) Name
* 2) Permission ..not available in MSDOS format list
* 3) Type
* 4) Owner ..not available in MSDOS format list
* 5) Group ..not available in MSDOS format list
* 6) Size

* Parse a UNIX format list. With skipping number of lines.
     * The columns of a typical UNIX format list is like:
     * drwxr-xr-x   6 appli    appli        1024 May 17 20:33 java
     * -rw-------   1 appli    appli        1005 May  1 21:21 mp3list
     * drwxr-xr-x   5 appli    appli        1024 May 17 16:56 perl
     * drwxr-xr-x   6 appli    appli        1024 Apr 30 23:18 public_html

// Some UNIX format list doesn't contain the column for group like this:
            // -rw-r--r--   1 daemon         0 Dec  7 10:15 .notar
            // -r--r--r--   1 daemon       828 Mar 30  1995 HOW_TO_SUBMIT
            // -r--r--r--   1 daemon       627 Mar 30  1995 README
            // -r--r--r--   1 daemon       876 Mar 30  1995 WELCOME
            // drwxr-xr-x   2 ftp          512 Oct 13  1999 bin

Solution

You can use SSH version string.

It is like:

• SSH-2.0-OpenSSH_5.3
• SSH-2.0-7.34 FlowSsh: Bitvise SSH Server (WinSSHD) 7.34
• SSH-2.0-1.36_sshlib GlobalSCAPE
• SSH-2.0-mod_sftp/0.9.8

In JSch you can retrieve it by using Session.getServerVersion.

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SFTP itself provides information about the remote system only using an optional extension "vendor-id", which is rarely supported. It's definitely not supported by JSch itself and neither by the most widespread SFTP server implementation, the OpenSSH.

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Though note that with SFTP, you typically do not need to parse the directory listing. In SFTP most of the listing data come in a form of binary structure, not a textual listing like with FTP.

Answered By - Martin Prikryl