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Syntax

cp SOURCE DEST
cp SOURCE... DIRECTORY

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Description

The cp command copies files from one location to another within Nash’s virtual filesystem. It can copy a single file to a new name or copy multiple files into a directory.
All copy operations happen within the VFS. To copy files between the host and VFS, you must use --bind mounts when launching Nash.

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Parameters

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SOURCE
string
required
Path to the source file(s) to copy. Can be relative or absolute.
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DEST
string
required
Destination path. If this is a directory, source file(s) will be copied into it with their original names. If this is a file path, the source will be copied with the new name.

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Behavior

  • Single file to file: cp file.txt newfile.txt creates a copy with a new name
  • File(s) to directory: cp file1.txt file2.txt dir/ copies both files into dir/
  • Directory detection: If destination exists and is a directory, files are copied into it
  • Name preservation: When copying into a directory, the basename of the source is preserved
  • Flag handling: Arguments starting with - are filtered out

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Examples

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Copy a single file

cp config.json config.backup.json

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Copy to a different directory

cp report.txt Documents/
The file report.txt is copied to Documents/report.txt.

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Copy multiple files to a directory

cp file1.txt file2.txt file3.txt backup/
All three files are copied into the backup/ directory with their original names.

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Copy with absolute paths

cp /home/user/data.csv /tmp/data.csv

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Overwrite existing file

cp new_config.json config.json
Nash’s cp will silently overwrite the destination file if it already exists. There is no -i (interactive) flag to prompt before overwriting.

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Error Handling

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Missing destination

cp source.txt

cp: missing destination operand
Exit code: 1

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Source file not found

cp nonexistent.txt dest.txt
Returns an error from the VFS layer describing that the source file doesn’t exist.

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Destination directory doesn’t exist

cp file.txt nonexistent_dir/
If nonexistent_dir/ doesn’t exist, the file will be created with the name nonexistent_dir/ (not recommended).

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Implementation Details

  • Source: src/builtins/cp.rs
  • Uses vfs.copy_file() for the actual copy operation
  • Filters arguments to separate flags from file paths
  • Automatically detects if destination is a directory using vfs.is_dir()
  • Preserves original filename when copying into directories using VfsPath::basename()
The current implementation only supports file copying. Directory copying (recursive -r flag) is not supported.

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Differences from Unix cp

FeatureUnix cpNash cp
Copy single file✅ Supported✅ Supported
Copy multiple files✅ Supported✅ Supported
Copy to directory✅ Supported✅ Supported
-r (recursive)✅ Supported❌ Not supported
-i (interactive)✅ Supported❌ Not supported
-v (verbose)✅ Supported❌ Not supported
-p (preserve)✅ Supported❌ Not applicable
-u (update)✅ Supported❌ Not supported
SymlinksDereferencesVFS has no symlinks

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Use Cases

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Backup configuration files

cp config.json config.json.backup

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Organize files

mkdir -p archive/2024
cp report.txt analysis.csv archive/2024/

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Duplicate for editing

cp template.sh my-script.sh

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Copy from mounted host directory

# Launch Nash with: nash --bind ./data:/data
cp /data/input.csv /home/user/input.csv

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Common Patterns

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Create a backup before editing

cp important.txt important.txt.bak
echo "new content" >> important.txt

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Copy all files matching a pattern (using find)

find . -name "*.txt" | while read f; do cp "$f" backup/; done
  • mv - Move or rename files
  • rm - Remove files
  • ls - List directory contents
  • mkdir - Create directories
  • stat - Check file information

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