12    Copying Files to Another Host

This chapter explains how to use operating system commands to perform the following tasks:

• Copy files between a local and a remote host

• Copy entire directories (including subdirectories) of files between a local and a remote host

• Copy files between two remote hosts

To determine the host name or online status of a remote host before copying files, use the finger, who, rwho, ping, or ruptime commands described in Chapter 10.

In addition to the information in this chapter, Chapter 14 provides information on using the UNIX-to-UNIX Copy Program (UUCP) to copy files to and from remote systems.

Note

The security features on the remote host determine whether or not you can copy a file. See your system administrator if you cannot copy a file.

12.1    Copying Files Between a Local and a Remote Host

You can use the following commands to copy files between a local and a remote host:

• rcp, described in Section 12.1.1; see Section 12.2 to copy entire directories of files. A host running the operating system can use rcp with a host running any other UNIX based operating system.

• ftp, described in Section 12.1.2. You can use ftp to copy files between hosts using operating systems that also support ftp.

• mailx, described in Section 12.1.3.

• write, described in Section 12.1.4.

12.1.1    Using rcp to Copy Files Between Local and Remote Hosts

When using rcp to copy files from a local to a remote host or from a remote to a local host, name the file to be copied first, followed by the destination file, as shown in this rcp syntax statement:

rcp [ option... ] localfile hostname:file

The localfile variable identifies the local file you want to copy. The hostname:file variable identifies the remote host (hostname) followed by a colon (:) and the name of the file (file) to which the local file is copied.

The following example uses rcp to copy the local file, YTD_sum from the directory /usr/reports on the local host to the file year-end in the directory /usr/acct on the remote host moon:

% rcp /usr/reports/YTD_sum  moon:/usr/acct/year-end

You can also send a file on the local host to a user at a remote host. The following example shows how to copy the file YTD_sum from the directory /usr/reports on the local host to the file acct_summaries in the home directory of user jones on the remote host moon:

% rcp /usr/reports/YTD_sum  jones@moon:acct_summaries

As used in the preceding examples, the rcp command assigns a new creation date and time to the file created from the original. It also assigns file read-write-execute permissions according to the host or user directory containing the newly created file.

You may need to preserve the original creation date and access permission mode of the copied file in the new file. As shown in the following example, the -p option enables you to preserve the original creation date and time and file access permission of YTD_sum in the file, year-end:

% rcp -p /usr/reports/YTD_sum  moon:/usr/acct/year-end

If the -p option was not entered, a new date and time would have been assigned, and the file access permission would be set to the default assigned by the system administrator for remote host, moon.

In the next example, the -p option preserves the same file creation and access permissions in the file acct_summaries as in the original file, YTD_sum:

% rcp -p /usr/reports/YTD_sum  jones@moon:acct_summaries

If the -p option was not entered, a new date and time would have been assigned, but unlike the previous example, the file access permission would be the default set by user jones through the umask command (if any) in the .login or .profile file. If the umask is not set in the .login or .profile file, the default for remote host moon determines the file access permission mode. See umask(1) for more information about setting umask.

To copy a file from a remote host to a local host, follow the following rcp syntax statement. The command syntax is the same as copying a local file to a remote host with the exception that localfile is the destination file, so it is placed last on the command line:

rcp [ option... ] hostname:file localfile

12.1.2    Using ftp to Copy Files Between Local and Remote Hosts

The ftp command is the interface to the File Transfer Protocol (FTP) and has an extensive set of subcommands (described in Table 12-1, Table 12-2, and Table 12-3) that support the main task of copying files. You can use the ftp command to copy files between any two hosts that support ftp.

See the ftp(1) reference page for a description of the ftp command options, which are used primarily for network administration tasks.

Copying files through FTP consists of the following steps:

1. Establishing a session on the remote host

2. Copying the files

3. Disconnecting the session

The ftp command has the following syntax:

ftp host_name

The host_name variable specifies the name of the host you want to reach. If you do not specify a host_name on the command line, you must use the ftp subcommand, open (described in Table 12-1) to connect with a remote host.

After you type ftp, the ftp> prompt is displayed and you are logged in to the remote host. You can then use ftp subcommands to perform the following tasks:

• Copy files (See Table 12-1)

• Append a local file to a remote file (See Table 12-1)

• Copy multiple files (See Table 12-1)

• List the contents of a remote directory (See Table 12-2)

• Change the current directory on the remote host (See Table 12-2)

• Delete files on remote hosts (See Table 12-2)

• Escape to the local shell to run commands (See Table 12-3)

Example 12-1 shows how user alice on local host earth logs on to remote host moon, and uses ftp subcommands to check the current working directory, list its contents, copy a binary file, and end the session.

Example 12-1:  Using ftp to Copy a File

earth% ftp moon [1]
Connected to moon
220 moon FTP server (Version  . . .) ready [2]
Name(moon:alice):[Return] [3]
Password: [4]
230 User alice logged in [5]
ftp> binary [6]
200 Type set to I
ftp> pwd [7]
257 "u/alice" is current directory
ftp> ls -l [8]
200 PORT command successful.
150 Opening data connection for /bin/ls (192.9.200.1,1026) (0 bytes)
total 2

-rw-r--r--   1 alice    system     101 Jun  5 10:03 file1

-rw-r--r--   1 alice    system     171 Jun  5 10:03 file2

-rw-r--r--   1 alice    system    1201 Jun  5 10:03 sales
ftp> get sales newsales [9]
200 PORT command successful.
150 Opening data connection for sales (192.9.200.1,1029) (1201 bytes)
226 Transfer complete.
local:sales remote:newsales
ftp> quit[10]
221 Goodbye.
earth% 

1. User alice enters the ftp command at the prompt of local host, earth to begin an ftp session with remote host, moon. [Return to example]

2. A message verifying the connection is displayed on the local host. [Return to example]

3. User alice presses Return at the prompt because her login name is the same on the remote host. [Return to example]

4. At the Password: prompt, user alice enters a valid password that is not displayed. [Return to example]

5. The login to the remote host is verified and the ftp> prompt appears, establishing the ftp session with the remote host. [Return to example]

6. User alice enters the binary subcommand at the ftp> prompt to set the file transfer type to binary and FTP verifies it with the message 200 Type set to I. [Return to example]

7. User alice enters the pwd subcommand to identify the current working directory, and FTP verifies it with the message u/alice is current directory. [Return to example]

8. User alice enters the ls -l subcommand to list the contents of the current working directory, file1, file2, and sales. [Return to example]

9. User alice copies the file sales from the remote host to a file called newsales on the local host through the get subcommand. [Return to example]

10. User alice enters the quit subcommand to end the ftp session and returns to the local system prompt. [Return to example]

Note

File transfers are subject to the security features on the remote host. If you cannot copy a file, see your system administrator.

Table 12-1 describes the ftp subcommands that copy files and exit ftp. The binary, get, and quit subcommands were used in Example 12-1.

Table 12-1:  The ftp Subcommands for Connecting to a Host and Copying Files

Table 12-2 describes the ftp subcommands that enable you to verify, change, or create the current directory and list its contents before you copy files, if necessary. The pwd and ls subcommands were used in Example 12-1.

Table 12-2:  The ftp Subcommands for Directory and File Modification

Table 12-3 describes the ftp subcommands that provide help or status information directly or by invoking the shell from within ftp.

Table 12-3:  The ftp Subcommands for Help and Status Information

The tftp command, which is the interface to the Trivial File Transfer Protocol (TFTP), provides another way of copying files. Unlike ftp, it does not provide subcommands for any other tasks and is recommended only for tasks performed by the superuser or the installer of the operating system (for example, copying the operating system kernel). Limited file access privileges are given to the remote tftp server daemon, tftpd. See the tftp(1) reference page for more information.

12.1.3    Using mailx to Copy ASCII Files Between Local and Remote Hosts

The mailx command copies ASCII files to a local or remote host, although mailx is most often used to send and receive mail messages as described in Chapter 11. You can copy an ASCII file to one or more users through mailx by using the left-angle bracket redirection symbol (<) as shown in the following syntax:

mailx [ option... ] recipient... < filename

The recipient variable specifies one or more user names or a mailx alias to whom you want to send the file, filename.

For example, to send the file schedule to several users, you could use the mailx command, as shown with its -s option that indicates the subject of the message:

% mailx -s "games" tom jeff craig jim ken < schedule

If you create a mail alias of wombats (See Section 11.6.1) for these five members of a team called Wombats, you can send the file to that alias, as shown:

% mailx -s "games" wombats < schedule

12.1.4    Using write to Copy Files Between Local and Remote Hosts

The write command copies files to a local or remote host, although write is most often used to write messages to other users as tasks described in Section 11.8. After you type write, enter the user name of the recipient, a left-angle bracket redirection symbol (<), and the name of the file you want to send. For example, to send a file named letter in your current directory to user maria, enter the following command at the host prompt:

% write maria < letter

12.2    Copying Directories of Files Between a Local and a Remote Host

The -r option of the rcp command enables you to copy entire directories of files recursively (that is, including files and directories within any subdirectories) between a local and a remote host.

To copy a directory recursively from your local host to a remote host, use the following syntax:

rcp -r localdirectory hostname:directory

The localdirectory variable identifies the local directory that you want to copy recursively. The hostname:directory variable identifies the remote host (hostname) followed by a colon (:) and the name of the remote directory (directory) to which the local directory is copied.

The following example uses rcp -r to copy recursively the directory /usr/reports from the local host to the directory /user/status/newdata on remote host moon:

% rcp -r /usr/reports  moon:/user/status/newdata

You can also copy recursively a directory on your local host to a user at a remote host. The following example shows how to copy the directory /usr/reports on the local host to the directory /user/status/newdata in the home directory of user smith on the remote host moon. This example also uses the -p option, as explained in Section 12.1.1, to preserve the original creation date and access permission mode of the directory and files that are copied in the new directory:

% rcp -p -r /usr/reports  smith@moon:/user/status/newdata

To copy a directory recursively from a remote host to your local host, follow the rcp syntax statement shown below. The command syntax is the same as copying a directory recursively from a local to a remote host with the exception that localdirectory is the destination file, so it is placed last on the command line:

rcp -r hostname:directorylocaldirectory

12.3    Copying Files Between Two Remote Hosts

From your local host, rcp can copy a file on one remote host to a file on another remote host. To do this, use the following rcp syntax:

rcp remhost1:filesendremhost2:file-recv

The remhost1 variable identifies the remote host containing the file you want to send, followed by a colon (:) and the file, filesend that you want to send. The last part of the statement identifies the second remote host, remhost2, and the file name, file-recv, to which the file from remhost1 will be copied. If only a directory name is given in file-recv (as in the example below), filesend will be copied there with the same file name.

The following example uses rcp to copy the file spark from the directory /u/cave/fred on remote host flint to the directory /u/hut/barney on remote host stone:

% rcp flint:/u/cave/fred/spark  stone:/u/hut/barney