When transferring files between Linux servers using SCP, many administrators encounter situations where the -p flag doesn't fully preserve ownership as expected. This becomes particularly problematic when:

• Copying system files owned by specific service users (like mysql, postgres, or www-data)
• Operating as root due to security constraints
• Maintaining consistent permissions across environments

The -p option in SCP preserves:

* Modification times
* Access times
* Modes (permission bits)

However, it doesn't preserve ownership because:

1. SCP doesn't have privilege escalation mechanisms
2. The remote server's user/group database might differ
3. Security restrictions prevent arbitrary ownership changes

Option 1: Post-transfer chown

After the transfer, modify ownership:

scp -p /mysql/serv/data_summary.* some_server:/mysql/test/
ssh some_server "chown -R mysql:mysql /mysql/test/"

Option 2: rsync with sudo

For more reliable permission handling:

rsync -avz --chown=mysql:mysql /mysql/serv/data_summary.* some_server:/mysql/test/

Note: This requires sudoers configuration allowing passwordless sudo for specific commands.

For complete metadata preservation:

rsync -aAXvz --numeric-ids --rsync-path="sudo rsync" \
      /mysql/serv/data_summary.* some_server:/mysql/test/

Key flags explanation:

• -a: archive mode (preserves almost everything)
• -A: preserves ACLs
• -X: preserves extended attributes
• --numeric-ids: uses IDs instead of names for ownership

When implementing these solutions:

• Limit sudo permissions to specific commands
• Consider using SSH certificates instead of passwords
• Audit permission changes regularly

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When transferring files between Linux servers using SCP, a common frustration occurs when file ownership and permissions don't carry over as expected - even when using the -p flag. This becomes particularly problematic when:

• Moving system files owned by specific services (like mysql)
• Root is required for the transfer due to admin policies
• The destination server needs identical ownership for proper functionality

The -p flag in SCP preserves:

 - Modification times
 - Access times
 - Mode (permission bits)

However, it cannot preserve ownership because:

1. SCP doesn't have the capability to map UIDs/GIDs between different systems
2. The remote system might not have matching user/group IDs
3. Even as root, SCP doesn't attempt to modify ownership during transfer

Here are three effective methods to achieve proper ownership preservation:

Method 1: Post-transfer chown

After SCP transfer, modify ownership:

scp -p /mysql/serv/data_summary.* some_server:/mysql/test/
ssh some_server "chown -R mysql:mysql /mysql/test/data_summary.*"

Method 2: rsync with --chown

rsync provides more granular control:

rsync -avp --chown=mysql:mysql /mysql/serv/data_summary.* some_server:/mysql/test/

Key advantages:

• Preserves all attributes including ownership
• Allows explicit ownership specification
• Supports incremental transfers

Method 3: Tar Pipe with Ownership Preservation

For complex transfers, consider:

(cd /mysql/serv && tar cf - data_summary.*) | \
ssh some_server "cd /mysql/test && tar xpf - --same-owner"

When implementing these solutions:

• Ensure the mysql user exists on both systems with matching UIDs
• Verify the destination directory permissions allow ownership changes
• Consider using --numeric-ids with rsync if UIDs differ between systems
• For large transfers, monitor progress with pv or rsync --progress

For frequent transfers, create a bash script:

#!/bin/bash
SOURCE_PATH="/mysql/serv/data_summary.*"
DEST="some_server:/mysql/test/"

rsync -avp --chown=mysql:mysql ${SOURCE_PATH} ${DEST} || {
  echo "rsync failed, falling back to scp+chown" >&2
  scp -p ${SOURCE_PATH} ${DEST}
  ssh ${DEST%:*} "chown mysql:mysql ${DEST#*:}data_summary.*"
}