Remote Copy (SSH)

BCMR supports copying files to and from remote hosts using SCP-like syntax over SSH.

Syntax

# Upload: local → remote
bcmr copy local_file.txt user@host:/remote/path/

# Download: remote → local
bcmr copy user@host:/remote/file.txt ./local/

# Recursive upload
bcmr copy -r local_dir/ user@host:/remote/path/

# Recursive download
bcmr copy -r user@host:/remote/dir/ ./local/

Parallel Transfers

Transfer multiple files concurrently with the -P flag:

# Upload 4 files in parallel
bcmr copy -P 4 file1.bin file2.bin file3.bin file4.bin user@host:/remote/

# Recursive upload with 8 workers
bcmr copy -r -P 8 ./large_dataset/ user@host:/data/

# Download multiple files in parallel
bcmr copy -P 3 user@host:/data/a.bin user@host:/data/b.bin ./local/

Default parallel count is configured in [scp] parallel_transfers (default: 4). When -P 1 or omitted on small transfers, files are sent sequentially.

Both TUI and plain text modes show per-worker status:

Uploading: [████████░░░░░░░░░░░░░░░░░░] 42% [3/4w]
150 MiB / 350 MiB | 45.5 MiB/s | ETA: 04:32
[1] large.iso 53% | [2] backup.tar 78% | [3] data.csv 12% | [4] idle

Compression

SSH compression can be enabled to reduce transfer time over slow links. Configure in [scp]:

Value	Behavior
"auto"	Enable compression if >30% of transfer bytes are compressible by extension (default)
"force"	Always enable SSH compression
"off"	Never compress

In auto mode, files with known compressed extensions (.gz, .zip, .mp4, .jpg, etc.) are counted as incompressible. If the majority of bytes are already compressed, compression is skipped to avoid CPU overhead.

How It Works

• Uses your existing SSH configuration (~/.ssh/config, keys, etc.)
• Validates SSH connectivity before starting transfers
• Reuses SSH connections via ControlMaster multiplexing
• Streams data through SSH with progress tracking
• Supports both upload and download directions

Limitations

• Cannot copy between two remote hosts directly — use a local intermediary
• Excludes and advanced copy features (reflink, sparse, resume) are not available for remote transfers

Path Detection

BCMR detects remote paths by the [user@]host:path format. These patterns are recognized as local paths and will not trigger remote mode:

• Absolute paths (/path/to/file)
• Relative paths (./file, ../file)
• Home directory (~/file)
• Windows drive letters (C:\file)