scp — remote file copy

💬 "scp command"

scp is file copying that operates over ssh. It is the simplest way to move one or two files.

For bulk or incremental transfers, rsync is better; scp is used for simple transfers.

• Concept: Uses ssh authentication as-is to copy files.
• Left argument: Source path. If remote, user@host:/path.
• Right argument: Destination path.
• Direction: Both local→remote and remote→local are possible.

Frequently used options

Three essential command combinations

• scp -i ~/.ssh/deploy app.tgz deploy@10.0.0.9:/tmp/ — Send the release file to the server
• scp -P 22022 deploy@10.0.0.9:/var/log/app/error.log ./ — Fetch the server log to the local machine
• scp -r -i ~/.ssh/deploy ./conf deploy@10.0.0.9:/tmp/conf — Transfer the entire configuration directory

💬 "Tell me common real-world mistakes and how to avoid them"

Here are common situations on live production servers, in order.

Step 1 · Transfer

Send the file to the target server.

scp -i ~/.ssh/deploy app-20261018.tgz deploy@10.0.0.9:/tmp/

Step 2 · Verification

Compare the size and checksum.

ssh deploy@10.0.0.9 'md5sum /tmp/app-20261018.tgz' && md5sum app-20261018.tgz

Step 3 · Apply

After verification, proceed with the deployment procedure.

ssh deploy@10.0.0.9 'tar xzf /tmp/app-20261018.tgz -C /opt/app/releases/20261018'

How this is used in practice

1. Transferring release files

Situation — Sending artifacts from the build server to the production server.

scp -i ~/.ssh/deploy dist/app.tgz deploy@10.0.0.9:/tmp/

Result — The file is transferred to /tmp and progress is displayed.

Point — Comparing checksums after transfer catches corrupted transfers immediately.

2. Retrieving incident logs

Situation — You need to analyze production server logs locally.

scp -i ~/.ssh/deploy deploy@10.0.0.9:/var/log/app/error.log /tmp/srv01-error.log

Result — The logs are copied locally so you can analyze them with convenient tools.

Point — For large logs, compress them before downloading or grep only the section you need.

Things to watch out for

• The port option is uppercase -P (ssh uses lowercase -p).
• scp does not support resuming or incremental transfer, so it is inefficient for large files.
• By default, scp does not fully preserve permissions and ownership.
• Do not overwrite production paths directly; download to /tmp and verify.

Actual execution screen

This is the result of transferring the release file and verifying its checksum.

!scp command execution result: file transfer and checksum

Live production server

Source (HTML): https://games.aidebatehub.com/programs/linux/remote/scp.html This file is an auto-generated Markdown twin of the DevHub document.