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help a newbie: how to read external hostfile list and execute a scp command to copy to listed hosts??

struct
New User

Feb 27, 2013, 6:36 PM

Post #1 of 3 (136 views)

help a newbie: how to read external hostfile list and execute a scp command to copy to listed hosts??	Can't Post

Hi I'm trying to write up a perl script which puts line string from a file in array and executes it with external command for each iteration.

so far the script can read from external file.
hosts file

Code

myhost1.test.com 
myhost2.test.com

massscp

Code

#!/usr/bin/perl -w 
use strict; 
use warnings; 
 
my $file = "hosts"; 
open (FH, "< $file") or die "Can't open $file for read: $!"; 
my @lines; 
while (<FH>) { 
    push (@lines, $_); 
} 
close FH or die "Cannot close $file: $!"; 
 
print @lines;    # output test

then I would like to execute a scp command to copy local file to the host listed on the list. for example:

scp file/to/trasfer $host:/tmp/

Please guide me.

rovf
Veteran

Feb 28, 2013, 3:12 AM

Post #2 of 3 (123 views)

Re: [struct] help a newbie: how to read external hostfile list and execute a scp command to copy to listed hosts?? [In reply to]	Can't Post

First, I would remove the trailing \n from the lines you read, before storing them into @lines:

Code

  chomp; 
  push @lines,$_;

An even better alternative would be to just transfer all the lines at once and omitting the push:

Code

open(my $fh,'<',$file) # This is the preferable way to use 'open' 
  or die "...."; 
my @lines = map {chomp;$_} (<$fh>); 
close $fh;

Of course the question is, *why* you need the content of the file stored in an array. Do you need it repeatedly? If you only need it for the scp, the array is unnecessary.

For running scp, you have two choices:

my $exitcode_and_errorcode=system("scp ....");

my $output=qx(scp ... 2>&1);

In the latter case, you get the output stored in a file. In the former one, the output goes to stdout/stderr.

FishMonger
Veteran

Feb 28, 2013, 6:47 AM

Post #3 of 3 (117 views)

Re: [rovf] help a newbie: how to read external hostfile list and execute a scp command to copy to listed hosts?? [In reply to]	Can't Post

Here are 2 other options for reading the file into an array. We would need to benchmark all of them to be sure, but I believe these are more efficient than the other options.

Code

my @lines = <$fh>; 
chomp @lines; 
 
# or we could combine the statements 
chomp(my @lines = <$fh>);

Code

use File::Slurp; 
 
my @lines = read_file( 'filename' { chomp => 1 } );

There are more than the 2 suggested choices for doing the scp.

You could use IPC::Run or one of its brothers, like IPC::Open2 or IPC::Open3. Or, you could use Net::SCP.

IPC::Run - system() and background procs w/ piping, redirs, ptys (Unix, Win32)
http://search.cpan.org/~toddr/IPC-Run-0.92/lib/IPC/Run.pm

Net::SCP - Perl extension for secure copy protocol
http://search.cpan.org/~ivan/Net-SCP-0.08/SCP.pm

Personally, I think I'd use Net::SCP because I like its OO interface more than the other options.

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