File-Remote
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NAME
File::Remote - Read/write/edit remote files transparently
SYNOPSIS
#
# Two ways to use File::Remote
#
# First, the function-based style. Here, we can use the
# special :replace tag to overload Perl builtins!
#
use File::Remote qw(:replace); # special :replace tag
# read from a remote file
open(REMOTE, "host:/remote/file") or die $!;
print while (<REMOTE>);
close(REMOTE);
# writing a local file still works!
open(LOCAL, ">>/local/file");
print LOCAL "This is a new line.\n";
close(LOCAL);
mkdir("host:/remote/dir", 0755);
unlink("host:/remote/file");
unlink("/local/file"); # still works too!
symlink("host:/remote/src", "host:/remote/dest");
chown("root", "other", "host:/remote/dir/file");
chmod(0600, "host:/remote/dir/file");
#
# Next, the object-oriented style, if you don't want to
# mess with the builtins.
#
use File::Remote;
my $remote = new File::Remote;
# Standard filehandles
$remote->open(FILE, ">>host:/remote/file") or die $!;
print FILE "Here's a line that's added.\n";
$remote->close(FILE);
# Create a new file and change its permissions
$remote->mkdir("host:/remote/dir");
$remote->touch("host:/remote/dir/file");
# Move files around
$remote->copy("/local/file", "host:/remote/file") or warn $!;
$remote->move("host:/remote/file", "/local/file");
# Read and write whole files
my @file = $remote->readfile("host:/remote/file");
$remote->writefile("/local/file", @file);
# Backup a file with a suffix
$remote->backup("host:/remote/oldfile", "save");
# Use secure connection methods
my $secure = new File::Remote (rsh => "/usr/local/bin/ssh",
rcp => "/usr/local/bin/scp");
$secure->unlink("/local/file");
$secure->rmdir("host:/remote/dir");
DESCRIPTION
This module takes care of dealing with files regardless of whether
they're local or remote. It allows you to create and edit files without
having to worry about their physical location on the network. If a file
passed into a function is of the form "host:/path/to/file", then
"File::Remote" uses rsh/rcp (or ssh/scp, depending on how you configure
it) to edit the file remotely. Otherwise, it assumes the file is local
and passes calls directly through to Perl's core functions.
The nice thing about this module is that you can use it for *all* your
file calls, since it handles both remote and local files transparently.
This means you don't have to put a whole bunch of checks for remote
files in your code. Plus, if you use the function-oriented interface
along with the ":replace" tag, you can actually redefine the Perl
builtin file functions. This means that your existing Perl scripts can
automatically handle remote files with no re-engineering(!).
There are two ways to program with "File::Remote", an object-oriented
style and a function-oriented style. Both methods work equally well,
it's just a matter of taste. One advantage of the object-oriented method
is that this allows you to read and write from different servers using
different methods (eg, rsh vs. ssh) simultaneously:
# Object-oriented method
use File::Remote;
my $remote = new File::Remote;
my $secure = new File::Remote (rsh => "/bin/ssh", rcp => "/bin/scp");
# Securely copy, write, and remove a file in one swoop...
$remote->open(LOCAL, "/local/file") or die "Open failed: $!\n";
$secure->open(REMOTE, "host:/remote/file") or die "Open failed: $!\n";
print REMOTE "$_" while (<LOCAL>);
$remote->close(LOCAL);
$secure->close(REMOTE);
# And let's move some files around securely
$secure->move("/local/file", "host:/remote/file");
$secure->copy("host:/remote/file", "/local/file");
To use the function-oriented interface, you must import the special tag
called ":replace" which will actually replace the Perl builtin
functions:
# Replace Perl's file methods with File::Remote's
use File::Remote qw(:replace);
open(FILE, ">host:/remote/file") or die "Open failed: $!\n";
print FILE "Hello, world!\n";
close(FILE) or die "Close failed: $!\n";
mkdir("/local/new/dir", "2775");
mkdir("host:/remote/new/dir");
chown("root", "other", "/local/new/dir");
unlink("host:/remote/file");
This is pretty neat; since "File::Remote" will pass calls to local files
straight through to Perl's core functions, you'll be able to do all this
"transparently" and not care about the locations of the files. Plus,
this has the big advantage of making your existing Perl scripts capable
of dealing with remote files without having to rewrite any code.
Because the names for the "File::Remote" methods clash with the Perl
builtins, if you use the function-oriented style with the ":standard"
tag there is an extra 'r' added to the front of the function names.
Thus, "<$remote-"open>> becomes 'ropen' in the ":standard"
function-oriented version:
# Function-oriented method
use File::Remote qw(:standard); # use standard function names
setrsh("/share/bin/ssh");
setrcp("/share/bin/scp");
# same functionality, but there's an "r" prefix
ropen(FILE, "host:/remote/file") or die "Open failed: $!\n";
print while (<FILE>);
rclose(FILE) or die "Close failed: $!\n";
runlink("host:/remote/file");
rmkdir("host:/remote/dir");
rchmod("0700", "host:/remote/dir");
That's kinda nasty, though. I recommend you use the ":replace" tag,
personally.
FUNCTIONS
Below are each of the functions you can make use of with "File::Remote".
Remember, for the function-oriented style, unless you use the ":replace"
tag you'll have to add an extra 'r' to the start of each function name.
For all functions, the file arg can be either local or remote.
new(opt => val, opt => val)
This is the main constructor when you're using the object-oriented
method of calling. You only need to use this if you're using the
object-oriented calling form. You can pass it three arguments which
change how it works:
rsh - path to your rsh or ssh program
rcp - path to your rcp or scp program
tmp - path to your tmp directory
So, for example:
use File::Remote;
my $secure = File::Remote->new(rsh => '/usr/local/bin/ssh',
rcp => '/usr/local/bin/scp',
tmp => '/var/run');
$secure->copy($src, $dest);
The above would setup your "$secure" object so that calls to methods on
it would use ssh and scp for connections.
setrsh(prog) ; setrcp(prog) ; settmp(dir)
These perform the equivalent functionality to setting the above flags,
for use in the function-oriented method of calling. So, if you were to
decide you didn't want to use the OO method, but instead wanted to use
the drop-in replacement function method (which I prefer):
use File::Remote qw(:replace);
setrsh('/usr/local/bin/ssh');
setrcp('/usr/local/bin/scp');
settmp('/var/run');
copy($src, $dest);
That chain of calls would have the exact same effect, only using the
function-oriented format instead of the object-oriented format.
open(HANDLE, file) ; close(HANDLE)
Used to open and close files just like the Perl builtins. These
functions accept both string filehandles and typeglob references, so any
valid Perl open calls:
open(FILE, ">> $file");
open(*FILE, ">$file");
open(\*FH, "< $file");
Should work, except for the 5.6 and later:
open(my $fh, $file);
This does not work when using "File::Remote". Patches to overcome this
are welcomed.
touch(file)
Updates the modification time on a file, or creates it if it doesn't
exist, just like the UNIX touch command.
mkdir(dir [, mode]) ; rmdir(dir [, recurse])
Create a dir with optional octal mode [mode]; remove a dir tree
optionally recursively. By default, rmdir works recursively, and the
mode of the new dir from mkdir depends on your umask.
copy(file1, file2)
Simply copies a file, just like File::Copy's function of the same name.
You can also address it as 'cp' (if you import the :aliases tag).
move(file1, file2)
Moves a file ala File::Copy. You can also address it as 'mv' (if you
import the :aliases tag).
chmod(mode, file) ; chown(owner, group, file)
Change the permissions or the owner of a file.
unlink(file)
Remove a file. You can also address it as 'rm' (if you import the
:aliases tag).
link(file1, file2)
Create a hard link between two files. The caveat to this function is
that both files must be local, or both files must be remote.
symlink(file1, file2)
Works just like link only creates symbolic instead of hard links.
readlink(file)
This reads what a symbolic link points to, just like the Perl builtin.
backup(file, [file|suffix])
This backs up a file, useful if you're going to be manipulating it. If
you just call it without the optional second filename or suffix, the
suffix 'bkup' will be added to the file. Either file can be local or
remote; this is really just a front-end to File::Remote::copy().
readfile(file) , writefile(file, @data)
These read and write whole files in one swoop, just like File::Slurp.
readfile() returns an array of the file, and writefile just returns
success or failure.
append(file, @data) , prepend(file, @data)
Similar to writefile(), only these don't overwrite the file, these
either append or prepend the data to the file.
EXAMPLES
Here's some more examples of how to use this module:
1. Add a new user to /etc/passwd on your server
This might be useful if you've got some type of web-based newuser
program that runs on a host other than the one you have to edit
/etc/passwd on:
# Function-oriented method
use File::Remote qw(:replace);
$passwd = "server:/etc/passwd";
backup($passwd, 'old'); # back it up to be safe
open(PASSWD, ">>$passwd") or die "Couldn't write $passwd: $!\n";
print PASSWD "$newuser_entry\n";
close(PASSWD);
2. Securely copy over a bunch of files
Hopefully you would use loops and variable names to make any actual code
( run in 0.851 second using v1.01-cache-2.11-cpan-5511b514fd6 )