📡 SCP · Secure Copy Protocol

Complete Guide to using SCP in Termux (Android) — Every command explained in English.

Encrypted file transfer between your Android device (Termux) and remote servers.

1. Overview

scp (Secure Copy Protocol) is a command-line tool that allows you to securely transfer files and directories between your Android device (using Termux) and a remote server over SSH.

📌 Common use cases:

Upload project files from Android to a Linux server.
Download files from a server to Android.
Backup files between devices.

2. Prerequisites & Installation

🔧 Step 1: Install OpenSSH in Termux

pkg update && pkg install openssh

📝 Explanation: Updates Termux package repositories and installs OpenSSH, which provides the scp, ssh, and related commands.

scp -V

🔍 Explanation: Displays the installed SCP version to verify OpenSSH is correctly installed.

which scp

📍 Explanation: Shows the location of the scp binary file (e.g., /data/data/com.termux/files/usr/bin/scp).

🔐 Step 2: Verify SSH Access

ssh ubuntu@115.178.135.124

🌐 Explanation: Attempts to log into the remote server as user ubuntu at the given IP. If SSH works, SCP will work as well.

✅ Note: SCP uses the same authentication and connection as SSH, so a successful SSH login is required.

3. Basic SCP Syntax

scp [options] source destination

📖 Structure: source = file/folder to copy from, destination = target location. Options like -r, -P, etc., modify behavior.

scp file.txt user@server:/path/

⬆️ Upload: Sends file.txt from your local machine to /path/ on the remote server.

scp user@server:/path/file.txt .

⬇️ Download: Retrieves file.txt from the server and saves it in the current local directory (denoted by .).

4. Uploading Files from Android to a Server

📁 Single file

scp /storage/emulated/0/Download/app.zip ubuntu@115.178.135.124:/home/ubuntu/

📦 Explanation: Copies app.zip from Android's Download folder to the Ubuntu user's home directory on the remote server.

📂 Multiple files

scp file1.txt file2.txt file3.txt ubuntu@115.178.135.124:/home/ubuntu/

📑 Explanation: Sends three files at once to the server in a single command.

5. Uploading Directories (Recursive)

scp -r /storage/emulated/0/Download/regapicta ubuntu@115.178.135.124:/home/ubuntu/upload/

🗂️ Explanation: The -r (recursive) flag uploads the entire regapicta folder and all its contents to /home/ubuntu/upload/ on the server.

6. Downloading Files from a Server to Android

⬇️ Download to current directory

scp ubuntu@115.178.135.124:/home/ubuntu/app.zip .

📥 Explanation: Downloads app.zip from the server and stores it in Termux's current working directory.

📀 Download to Android Download folder

scp ubuntu@115.178.135.124:/home/ubuntu/app.zip /storage/emulated/0/Download/

📲 Explanation: The file is saved directly to Android's internal storage Download folder, making it accessible by other apps.

7. Downloading Directories (Recursive)

scp -r ubuntu@115.178.135.124:/home/ubuntu/project /storage/emulated/0/Download/

📁 Explanation: Downloads the entire project folder from the server (including all subdirectories) to Android's Download folder.

8. Using a Custom SSH Port

⚠️ Important: scp uses uppercase -P (not lowercase -p).

scp -P 2222 app.zip ubuntu@115.178.135.124:/home/ubuntu/

🔌 Explanation: Specifies port 2222 for the SSH connection (default is 22). Useful when the server listens on a non-standard port.

9. Using SSH Keys (Passwordless & Secure)

scp -i ~/.ssh/id_rsa app.zip ubuntu@115.178.135.124:/home/ubuntu/

🔑 Explanation: -i specifies a private key file (e.g., id_rsa) for authentication. More secure and avoids password prompts.

scp -i ~/.ssh/id_rsa ubuntu@115.178.135.124:/home/ubuntu/app.zip .

🔐 Explanation: Downloads a file from the server using key-based authentication. Ideal for automated scripts.

10. Viewing Transfer Progress (Verbose Mode)

scp -v app.zip ubuntu@115.178.135.124:/home/ubuntu/

🐞 Explanation: -v (verbose) prints detailed connection steps, SSH negotiation, and transfer progress — excellent for debugging.

scp -rv project ubuntu@115.178.135.124:/home/ubuntu/

📢 Explanation: Combines -r (recursive) with -v (verbose) for full logging of directory transfers.

11. Compression During Transfer (Faster Transfers)

scp -rC project ubuntu@115.178.135.124:/home/ubuntu/

🗜️ Explanation: The -C flag enables on-the-fly compression, reducing bandwidth usage and speeding up transfers of large folders.

12. Accessing Android Storage in Termux

termux-setup-storage

📂 Explanation: One-time command to grant Termux access to Android's shared storage. Creates the symlink /storage/emulated/0.

cd /storage/emulated/0/Download

📁 Explanation: Navigates to the internal Download directory, a common location for files to upload.

Location	Path
📱 Internal Storage	/storage/emulated/0
📥 Download	/storage/emulated/0/Download
📸 DCIM	/storage/emulated/0/DCIM
🖼️ Pictures	/storage/emulated/0/Pictures
📄 Documents	/storage/emulated/0/Documents

13. Real-World Examples

📦 Upload Regapicta Project

scp -r /storage/emulated/0/Download/regapicta ubuntu@115.178.135.124:/home/ubuntu/upload/

🚀 Explanation: Sends a development project folder from Android to a dedicated upload directory on the server.

📄 Upload requirements.txt

scp requirements.txt ubuntu@115.178.135.124:/home/ubuntu/upload/

🐍 Explanation: Transfers a Python dependencies file to the server for application deployment.

🐍 Upload Flask Application

scp -r flask_app ubuntu@115.178.135.124:/home/ubuntu/apps/

🌐 Explanation: Uploads an entire Flask web app directory to the server's apps folder.

📥 Download OCR Results

scp ubuntu@115.178.135.124:/home/ubuntu/output.json /storage/emulated/0/Download/

📄 Explanation: Fetches a JSON results file from the server and saves it to Android's Download folder.

14. Troubleshooting & Solutions

🔒 Permission Denied

ssh ubuntu@115.178.135.124

🔍 Explanation: Test SSH connectivity first. If SSH fails, SCP will also fail. Check username, keys, or server permissions.

📂 No Such File or Directory

ls -la /path/expected

📁 Explanation: Verify that the source or destination path exists. Use ls to confirm file/folder presence.

🚫 Connection Refused

🛡️ Possible causes: SSH service not running on server, wrong port, or firewall blocking. On the server, check with sudo systemctl status ssh.

⏱️ Timeout

ping 115.178.135.124

📡 Explanation: Check network connectivity. If ping fails, verify IP address, internet connection, or ISP restrictions.

15. Recommended Workflow (Android → Ubuntu Server)

ssh ubuntu@115.178.135.124 → Test connection
scp -r regapicta ubuntu@115.178.135.124:/home/ubuntu/upload/ → Upload project
ssh ubuntu@115.178.135.124 → Log into server
cd /home/ubuntu/upload && ls -la → Verify upload
cd regapicta && python -m venv venv && source venv/bin/activate && pip install -r requirements.txt → Deploy application

⚡ Cheatsheet with Explanations

📤 Upload file
scp file.txt user@server:/path/
Copy local file to remote server

📁 Upload folder
scp -r folder user@server:/path/
Recursive copy of entire directory

📥 Download file
scp user@server:/path/file.txt .
Save remote file to current local directory

🗂️ Download folder
scp -r user@server:/path/folder .
Download directory recursively

🔌 Custom port
scp -P 2222 file.txt user@server:/path/
Specify SSH port (uppercase P)

🔑 SSH key
scp -i ~/.ssh/id_rsa file.txt user@server:/path/
Authenticate using private key

🗜️ Compression
scp -rC folder user@server:/path/
Enable compression for speed

🐞 Verbose debug
scp -v file.txt user@server:/path/
See detailed transfer logs

💡 Key takeaway: Every SCP command follows the pattern source → destination, with options for recursion, port changes, key authentication, or compression.