Net::SCP3pm

Usage

  #procedural interface
  use Net::SCP qw(scp iscp);
  scp($source, $destination);
  iscp($source, $destination); #shows command, asks for confirmation, and
                               #allows user to type a password on tty
  #OO interface
  $scp = Net::SCP->new( "hostname", "username" );
  #with named params
  $scp = Net::SCP->new( { "host"=>$hostname, "user"=>$username } );
  $scp->get("filename") or die $scp->{errstr};
  $scp->put("filename") or die $scp->{errstr};
  #tmtowtdi
  $scp = new Net::SCP;
  $scp->scp($source, $destination);
  #Net::FTP-style
  $scp = Net::SCP->new("hostname");
  $scp->login("user");
  $scp->cwd("/dir");
  $scp->size("file");
  $scp->get("file");

Overview

Simple wrappers around ssh and scp commands.

Subroutines

scp SOURCE, DESTINATION

Can be called either as a subroutine or a method; however, the subroutine interface is deprecated.

Calls scp in batch mode, with the -B -p -q and -r options. Returns false upon error, with a text error message accessible in $scp->{errstr}.

Returns false and sets the errstr attribute if there is an error.

iscp SOURCE, DESTINATION

Can be called either as a subroutine or a method; however, the subroutine interface is deprecated.

Prints the scp command to be execute, waits for the user to confirm, and (optionally) executes scp, with the -p and -r flags.

Returns false and sets the errstr attribute if there is an error.

Methods

new HOSTNAME [ USER ] | HASHREF

This is the constructor for a new Net::SCP object. You must specify a hostname, and may optionally provide a user. Alternatively, you may pass a hashref of named params, with the following keys:

    host - hostname
    user - username
    interactive - bool
    cwd - current working directory on remote server

login [USER]

Compatibility method. Optionally sets the user.

cwd CWD

Sets the cwd (used for a subsequent get or put request without a full pathname).

get REMOTE_FILE [, LOCAL_FILE]

Uses scp to transfer REMOTE_FILE from the remote host. If a local filename is omitted, uses the basename of the remote file.

mkdir DIRECTORY

Makes a directory on the remote server. Returns false and sets the errstr attribute on errors.

(Implementation note: An ssh connection is established to the remote machine and '/bin/mkdir -p' is used to create the directory.)

size FILE

Returns the size in bytes for the given file as stored on the remote server. Returns 0 on error, and sets the errstr attribute. In the case of an actual zero-length file on the remote server, the special value '0e0' is returned, which evaluates to zero when used as a number, but is true.

(Implementation note: An ssh connection is established to the remote machine and wc is used to determine the file size.)

put LOCAL_FILE [, REMOTE_FILE]

Uses scp to trasnfer LOCAL_FILE to the remote host. If a remote filename is omitted, uses the basename of the local file.

binary

Compatibility method: does nothing; returns true.

quit

Compatibility method: does nothing; returns true.

Frequently asked questions

Q: How do you supply a password to connect with ssh within a perl script using the Net::SSH module?

A: You don't (at least not with this module). Use RSA or DSA keys. See the
quick help in the next section and the ssh-keygen(1) manpage.

A #2: See Net::SCP::Expect instead.

Q: My script is "leaking" scp processes.

A: See "How do I avoid zombies on a Unix system" in perlfaq8, IPC::Open2, IPC::Open3 and "waitpid" in perlfunc.

Generating and using SSH keys

1 Generate keys

Type:

   ssh-keygen -t rsa

And do not enter a passphrase unless you wanted to be prompted for one during file copying.

Here is what you will see:

   $ ssh-keygen -t rsa
   Generating public/private rsa key pair.
   Enter file in which to save the key (/home/User/.ssh/id_rsa):
   Enter passphrase (empty for no passphrase):
   Enter same passphrase again:
   Your identification has been saved in /home/User/.ssh/id_rsa.
   Your public key has been saved in /home/User/.ssh/id_rsa.pub.
   The key fingerprint is:
   5a:cd:2b:0a:cd:d9:15:85:26:79:40:0c:55:2a:f4:23 User@JEFF-CPU

2 Copy public to machines you want to upload to

"id_rsa.pub" is your public key. Copy it to "~/.ssh" on target machine.

Put a copy of the public key file on each machine you want to log into. Name the copy "authorized_keys" (some implementations name this file "authorized_keys2")

Then type:

     chmod 600 authorized_keys

Then make sure your home dir on the remote machine is not group or world writeable.