Perl

Resolve an Absolute Remote Path with SFTP RealPath

Demonstrates the Chilkat SFtp.RealPath method, which asks the server to canonicalize a path and returns the resulting absolute remote path. The first argument is the original path and the second is an optional compose path (SFTP v5 or later); pass an empty string when no composition is needed.

Background: The server — not the client — owns the remote filesystem's layout, so path canonicalization must happen on the server. RealPath resolves ., .., and symbolic links into a single absolute path, which is the reliable way to learn the session's home directory (canonicalize .) or to turn a relative path into an absolute one before storing or displaying it. On SFTP v5 and later, the compose path can additionally join or override the original.

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use strict;
use warnings;
use Chilkat2;

# Demonstrates the SFtp.RealPath method, which asks the server to canonicalize a path and
# returns the resulting absolute remote path.  The 1st argument is the original path and the
# 2nd is an optional compose path (SFTP v5+), which may be an empty string.

my $sftp = Chilkat2::SFtp->new;

# Step 1: Connect the SSH transport.  Port 22 is the usual port.
my $port = 22;
my $success = $sftp->Connect('sftp.example.com', $port);
if (!$success) {
    print $sftp->LastErrorText, "\n";
    exit;
}

# Normally you would not hard-code the password in source.  You should instead obtain it
# from an interactive prompt, environment variable, or a secrets vault.
my $password = 'mySshPassword';

$success = $sftp->AuthenticatePw('mySshLogin', $password);
if (!$success) {
    print $sftp->LastErrorText, "\n";
    exit;
}

# Step 3: Open the SFTP subsystem.  This must be done after authentication and before any
# file or directory operations.
$success = $sftp->InitializeSftp();
if (!$success) {
    print $sftp->LastErrorText, "\n";
    exit;
}

# Resolve "." to the absolute path of the session's default (home) directory.  No compose path
# is needed, so the 2nd argument is an empty string.
my $homeDir = $sftp->RealPath('.', '');
if (!$sftp->LastMethodSuccess) {
    print $sftp->LastErrorText, "\n";
    exit;
}

print 'Home directory: ', $homeDir, "\n";

# Canonicalize a relative path with "..", resolving it to an absolute path.
my $resolved = $sftp->RealPath('subdir/../otherdir', '');
if (!$sftp->LastMethodSuccess) {
    print $sftp->LastErrorText, "\n";
    exit;
}

print 'Resolved path: ', $resolved, "\n";

$sftp->Disconnect();