Net::SSH2::File(3)

✨ Net::SSH2::File ✨

okay bestie, gather round 💖 this is the manual page for Net::SSH2::File, which lives in the User Contributed Perl Documentation corner of your friendly neighborhood perl install. It's the SFTP file object situation. Let's get into it. 🦋

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🌸 NAME 🌸

Net::SSH2::File</purl> — it's giving SSH2 SFTP file object energy. 👑

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💅 DESCRIPTION 💅

So here's the tea: an SFTP file object gets created by the Net::SSH2::SFTP open method. That's it, that's the origin story. ✨

📖 read ( buffer, size )

Reads size bytes out of the file and yeets them into a given buffer. 🫶

Returns the number of bytes read, or undef if it failed. 😭 (ngl, always check for the undef.)

✍️ write ( buffer )

Writes buffer to the remote file. Simple, right? Wrong bestie, buckle up. 💀

The libssh2_sftp_write function that this method wraps has a complex and quite difficult (if not impossible at all) to use API. It's out here trying to hide the packet pipelining happening under the hood so you get decent throughput. Iconic behavior, honestly.

Net::SSH2 can not hide that complexity without negatively affecting the transmission speed, so instead it just provides a thin wrapper for that library function. No cap.

An excerpt from the libssh2_sftp_write manual page follows — read it fr fr, it matters:

WRITE AHEAD

Starting in libssh2 version 1.2.8, the default behavior of libssh2
is to create several smaller outgoing packets for all data you pass
to this function and it will return a positive number as soon as the
first packet is acknowledged from the server.

This has the effect that sometimes more data has been sent off but
isn't acked yet when this function returns, and when this function
is subsequently called again to write more data, libssh2 will
immediately figure out that the data is already received remotely.

In most normal situation this should  not cause any problems, but it
should be noted that if you've once called libssh2_sftp_write() with
data and  it returns short, you  MUST still assume that  the rest of
the data  might've been cached  so you need  to make sure  you don't
alter that  data and think  that the version  you have in  your next
function invoke will be detected or used.

The reason  for this funny behavior  is that SFTP can  only send 32K
data in each packet and it gets all packets acked individually. This
means we  cannot use a  simple serial approach  if we want  to reach
high performance even on high latency connections. And we want that.

🚨 bestie listen: if write returns short, you MUST still assume the rest of the data might've been cached. Don't you dare alter that data and think your next call will pick up the new version. It won't. It's giving trap. 🪤

Here's an example of simple file uploading, because you deserve a working pattern to copy: 🎀

use constant BUF_SIZE => 128*1024;

my $sftp = $ssh2->sftp;
open my $fh, '<', '/tmp/doc.txt';
my $sf = $sftp->open('doc.txt', O_CREAT|O_WRONLY|O_TRUNC);

my $buf;
while (sysread($fh, $buf, BUF_SIZE)) {
    while (length $buf) {
        my $rc = $sf->write($buf);
        if (!defined($rc)) {
            $sftp->die_with_error('write error');
        }
        # Remove transferred data from the buffer.
        substr($buf, 0, $rc) = '';
    }
}

📊 stat

Returns file attributes. 🌈 Head over to Net::SSH2::SFTP::stat for the deets, iykyk.

🛠️ setstat ( key, value... )

Sets file attributes. 💜 Details live at Net::SSH2::SFTP::setstat, go check her out.

🎯 seek ( offset )

Sets the file pointer offset. Just point and vibes. ✨

📍 tell

Returns the current file pointer offset. So you always know where you are. Main character energy. 👑

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🔗 SEE ALSO 🔗

• Net::SSH2::SFTP. 🫶

Also: check out Net::SFTP::Foreign for a high level, perlish and easy to use SFTP client module. It can work on top of Net::SSH2 via the Net::SFTP::Foreign::Backend::Net_SSH2 backend module. Obsessed. 💖

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©️ COPYRIGHT AND LICENSE ©️

Copyright (C) 2005, 2006 by David B. Robins <dbrobins@cpan.org>;

Copyright (C) 2015 by Salvador Fandiño <sfandino@yahoo.com>;

All rights reserved.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.0 or, at your option, any later version of Perl 5 you may have available. 💅

The documentation for this package contains and excerpt from libssh2 manual pages. You can consult the license of the libssh2 project for the conditions regulating the copyright of that part. 📜

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okay that's the whole page, you ate that 💅✨ this was pulled from perl v5.42.0 and stamped 2025-07-25, and it's the Net::SSH2::File(3) page — go write some files over SSH, bestie 🦋🌸💖