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My Linux Upskill Challenge - Day 12

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My Linux Upskill Challenge - Day 12

This is my technical journal note following the Lesson 12 of the Linux Upskill Challenge by Steve Brorens / Livia Lima

Text Lesson: Day 12 - Transfering files

NOTE

Disclaimer: This is premium content written with care by an actual human 👨! Struggling in the middle of the curve of getting used to writing on Neovim, which English is not his first language 🫶.

Introduction

This lesson is about Transferring Files in Linux.

There exists a wide range of ways a Linux server can share files, including:

  • SMB: the Microsoft’s file sharing system
  • AFP: Apple’s file sharing, never heard before
  • WebDav: Sharing over web (http) protocol
  • FTP: The old, legacy and insecure File Transfer Protocol
  • scp: Simple support for copying files
  • rsync: Fast, very efficient file copying
  • SFTP: SSH File Transfer Protocol, it allows to access and copying files over SSH protocol (Despite the name, at technical level it’s completely different to the traditional FTP)

SFTP

The SSH File Transfer Protocol (as defined in the IETF draft) it’s the first options for managing files on a remote Linux server. Here are some of its main advantages:

  • No extra setup is required on your server
  • Provides strong built-in encryption
  • Allows browsing through the directory structure
  • You can create and delete folders

If you are able to logging to a server via ssh, you’ll also be able to use SFTP, because both use the same underlying protocol.

On the other hand, setting up your server for any other file transfer protocols usually involves some extra configuration. More importantly, enabling additional protocols and services, often means opening extra ports, which increases you server “attack surface”.

Traditional FTP is still used in some places, but it’s important to remember that FTP transmits both login credentials and data in plain text. This means anyone who intercepts the traffic could easily read everything — including your username and password.

SFTP on Linux

  • SFTP requires both a server and a client to function.
  • Most Linux distributions include the necessary software to act as both an SFTP server and client.

SFTP Server on Linux

  • Most modern Linux distributions use OpenSSH as their SSH server.
  • Since SFTP is a built-in subsystem of OpenSSH, there’s no need to install a separate FTP server.
  • You can confirm this in the SSH server configuration file (/etc/ssh/sshd_config) by looking for the following line:
Subsystem       sftp    /usr/lib/openssh/sftp-server

SFTP Client on Linux

  • The OpenSSH client includes the sftp command
  • If you’re using a Linux with desktop, you already have a FTP Client on the file manager.
  • This note is about Linux, but in case you need to connect via SFTP to a Linux Server from a Windows or Mac computer, you have several options to install as a SFTP clients, such as:
    • WinSCP or FileZilla - for Windows
    • CyberDuck or FileZilla - for MacOs

SFTP Operations

Start a SFTP connection to a server

  • Because SFTP and SSH use the same protocol at the background, you can authenticate using the same SSH key. Basically you only need to change the command from ssh to sftp as follows:
❯ sftp -i ~/keys/linux.pem carlos@192.168.1.29
Connected to 192.168.1.29.
sftp>
  • The prompt is different than a SSH session: sftp> .
  • You can close the SFTP session with quit

Local vs Remote

  • You’ll often need to check or manipulate files and directories both on your local machine and on the remote server — for example, running commands like pwd, ls, mkdir, etc.
  • Instead of constantly switching back and forth between windows or panes, fortunately, there’s a way to differentiate commands that apply to your local machine by simply prefixing them with the letter l.
  • For instance with pwd we can check the current directory on the remote server
sftp> pwd
Remote working directory: /home/carlos
  • And lpwd shows you where are you located on your machine.
 
sftp> lpwd
Local working directory: /Users/carlos.ramirez/tutorial

  • This also works for ls and… yes, your right: lls, as we can see here:

    • Remote
    sftp> ls
code         listing.txt  summary.md   testfile
    • Local
    sftp> lls
another-file.txt        local-file.md

Upload a local file to server

  • Use the command put to upload a local file to a remote server via FTP
sftp> put local-file.md
Uploading local-file.md to /home/carlos/local-file.md
local-file.md                                                                                                                100%   12     5.9KB/s   00:00

Download a remote file from the server

  • Use the command get to download a remote file from a remote server to your computer
sftp> get testfile
Fetching /home/carlos/testfile to testfile
testfile                                                                                                                                  100%   13KB   2.9MB/s   00:00
sftp> lls
another-file.txt        listing.txt             local-file.md           testfile
sftp>

Upload multiple files to the server

  • Use mput, (m is for multiple) to upload several file with a single command to the server
sftp> mput *.txt
Uploading another-file.txt to /home/carlos/another-file.txt
another-file.txt                                                                                                                          100%   17     8.7KB/s   00:00
Uploading listing.txt to /home/carlos/listing.txt
listing.txt                                                                                                                               100%  378   299.6KB/s   00:00
sftp> ls
another-file.txt   code               listing.txt        local-file.md      summary.md         testfile
sftp>

Download multiple files from the server

  • The same way you can use mget to download several files from the server.
sftp> mput *.txt
Uploading another-file.txt to /home/carlos/another-file.txt
another-file.txt                                                                                            100%   17     7.5KB/s   00:00
Uploading another.txt to /home/carlos/another.txt
another.txt                                                                                                 100%    0     0.0KB/s   00:00
Uploading listing.txt to /home/carlos/listing.txt
listing.txt                                                                                                 100%  378   249.6KB/s   00:00
Uploading thisfile.txt to /home/carlos/thisfile.txt
thisfile.txt                                                                                                100%    0     0.0KB/s   00:00
sftp> ls
another-file.txt    another.txt         code                listing.txt         local-file.md       summary.md          testfile
thisfile.txt
sftp>

FileZilla

  • FileZilla it´s is a solution that offers two main applications, a SFTP client and a SFTP server, both with a Graphical user interface,
  • They are are available for Linux, Windows and MacOS
  • In this case, we need to install on our computer the client application, and the Linux VM is our SFTP server.
  • With Filezilla SFTP client we can do pretty much the same operations we did with the terminal end the sftp command.

rsync

rsync it’s another program to transfer files between Linux systems, however it works a little different, with rsync, you can syncrhonize to locations, which can be on the same computers or across the network.

Normally is used for backups, mirroring and deployment scripts.

How to use it

This is my local directory (on my computer): ~/tutorial/

-rw-r--r--@ 1 carlos.ramirez  staff   0 Aug 11 17:56 hello.md
-rw-r--r--@ 1 carlos.ramirez  staff  95 Aug 20 17:32 holamundo.md
-rw-r--r--@ 1 carlos.ramirez  staff  12 Jul 24 21:01 local-file.md
-rw-r--r--@ 1 carlos.ramirez  staff  14 Aug 11 19:10 thisfile.txt

I created a remote directory on the server at: ~/remote_dir

 mkdir remote_dirr

With the following command I copied the folders on my local directory (~/tutorial) to the remote folder on the server (~/remote_dir):

  • Located on my $HOME directory:
rsync -e "ssh -i ~/keys/linux.pem" -av tutorial/ carlos@192.168.1.29:remote_dir

And this is was the output:

Transfer starting: 5 files
./
hello.md
holamundo.md
local-file.md
thisfile.txt
 
sent 536 bytes  received 114 bytes  309523 bytes/sec
total size is 121  speedup is 0.19

So when I looked at the remote server, I could see the same files on my local folder, copied to the remote folder

Last login: Wed Aug 20 17:49:44 2025 from 192.168.1.26
❯ cd remote_dir
❯ ls -l
total 12
-rw-r--r-- 1 carlos carlos  0 Aug 11 17:56 hello.md
-rw-r--r-- 1 carlos carlos 95 Aug 20 17:32 holamundo.md
-rw-r--r-- 1 carlos carlos 12 Jul 24 21:01 local-file.md
-rw-r--r-- 1 carlos carlos 14 Aug 11 19:10 thisfile.txt

Now let make some change son the local server, like adding a file or editing an existing one.

❯ cd tutorial
❯ echo "This is the new line" >> hello.md
❯ touch a_new_file.md

Then let’s sync the local to the remote directory again

--- 20 Agosto — voy por aqui ----

rsync -e “ssh -i ~/keys/linux.pem” -av tutorial/ carlos@192.168.1.29:remote_dir

Transfer starting: 10 files ./ newfile.txt thisfile.txt

sent 517 bytes received 70 bytes 279523 bytes/sec total size is 13568 speedup is 23.11 ~   ✔

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