Communications

File Transfer


This section describes how to copy a file between two VMS systems using the COPY command, and between a VMS system and another computer using FTP or Kermit.

Remote File Access

Remote file access may be made on either the file or record level, but only file level access is discussed here. To access a file, you use normal VMS commands, such as COPY or TYPE, but you specify the file name differently.

A full file specification for a file on a remote node takes the following form:

node::disk:[directory]filename.type;version
For example, if you are logged on the host IDTVAX and you want to make a copy of a file on KEPLER, you might type the following command:

$ COPY KEPLER::DISK$SHARE0:[VIRGINIA]SMITH.DAT;1 *.*
This will work for most types of remote file access that you might need to do--as long as you have appropriate permission to access the file. Otherwise, it is possible to pass a username and password to the remote host. This is done by enclosing the login information in quotes next to the node name. For example, if the file we tried to copy in the previous example was unsuccessful, you might need to add your account name and password for the remote system, so your command might look like the following:

$ COPY node"username password"::DISK$SHARE0:[SMTH]FILE.DAT;1 *.*

FTP

To transfer files between systems on the network (for example, retrieving files over the Internet), you would use the FTP command. Before starting the program, you should move to the directory on your local system into--or from--which you will move files. It is also possible to move around local directories from within FTP by using the command lcd.

The program can be invoked by either supplying a destination address on the command line, for example, ftp ftp.stsci.edu, or by simply typing ftp and then typing the open command, for example, open ftp.stsci.edu. You will then be connected to the remote machine and asked for your username and password. Table 8.4 describes some of the most useful FTP commands. Figure 8.9 shows a sample FTP session.



Table 8.4: Basic FTP Commands

You will occasionally, usually from the Usenet news, be invited to obtain files via anonymous FTP. To get these files, you need to open a connection to the remote machine, and when prompted for a user name, type the word anonymous. You will then be prompted for a password. At the password prompt enter your e-mail address. You will then be logged in and able to transfer files. Figure 8.9 is a sample anonymous FTP session to the node stsci.edu.



Figure 8.9: Sample Anonymous FTP Session

Kermit

The Kermit file transfer protocol was developed at Columbia University to allow file transfers between heterogeneous systems. It is frequently implemented in communications software for microcomputers (including Macintoshs, Amigas, and PC clones) as one option for file transfers--it is the most practical option for users who want to transfer files between their Institute VMS accounts and their home computers. To use Kermit:

  1. Start your communications software on your home computer as you normally do and dial in to the Institute's modem pool. You will connect to the Xyplex as described on page 1. Login to the VMS system as you normally do.

  2. Start Kermit on the VMS host by typing kermit.

  3. To send a file from the VMS host to your home PC, type send file and then start the download procedure from your home PC.

  4. To upload a file from your home PC to the VMS host, type rec file and then start the upload procedure from your home PC.

  5. Exit from Kermit by typing EXIT.

From within Kermit, you can get a list of available commands by pressing . For more details, see the C-Kermit User Guide, which is available from the Science Software Support Office at STScI.

Kermit offers a number of other features for users willing to delve into its depths. It is also possible to automate your file transfers using scripts in conjunction with the Kermit TAKE command. These features are beyond the scope of this document and are described in the C-Kermit User Guide. File transfers over the network can also be done using Kermit, however, FTP is the preferred method.

Remote File Access
FTP
Table 8.4: - Basic FTP Commands
Figure 8.9: - Sample Anonymous FTP Session
Kermit

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