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Syntax

mv SOURCE DEST

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Description

The mv command moves or renames files and directories within Nash’s virtual filesystem. Unlike cp, this is a true move operation - the source is removed after the destination is created.
In Nash’s VFS, mv is implemented using vfs.rename() which is an atomic operation within the in-memory filesystem.

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Parameters

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SOURCE
string
required
Path to the source file or directory to move. Can be relative or absolute.
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DEST
string
required
Destination path. If this is an existing directory, the source will be moved into it with its original name. Otherwise, the source is renamed to this path.

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Behavior

  • Rename file: mv old.txt new.txt renames the file
  • Move to directory: mv file.txt dir/ moves file into directory as dir/file.txt
  • Move directory: Works with both files and directories
  • Atomic operation: The move/rename is a single VFS operation
  • Flag handling: Arguments starting with - are filtered out but not validated

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Examples

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Rename a file

mv old_name.txt new_name.txt

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Move file to a directory

mv report.txt Documents/
The file is moved to Documents/report.txt (original name preserved).

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Rename a directory

mv old_folder new_folder

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Move multiple files with a script

for f in *.txt; do
  mv "$f" archive/
done

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Move with absolute paths

mv /tmp/temp_file.txt /home/user/permanent.txt

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Organize files by moving

mkdir -p sorted/docs sorted/images
mv *.txt sorted/docs/
mv *.png sorted/images/

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Error Handling

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Missing destination

mv source.txt

mv: missing destination operand
Exit code: 1

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Source doesn’t exist

mv nonexistent.txt somewhere.txt
Returns an error from the VFS layer indicating the source file doesn’t exist.

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Destination already exists

If the destination path exists as a file (not a directory), mv will overwrite it without prompting.
mv will silently overwrite destination files. There is no -i (interactive) flag to prompt before overwriting.

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Implementation Details

  • Source: src/builtins/mv.rs
  • Uses vfs.rename() for the actual move operation
  • Only processes the first non-flag argument as source
  • Automatically detects if destination is a directory using vfs.is_dir()
  • Preserves basename when moving into directories using VfsPath::basename()
  • Does not support moving multiple files in a single command
Unlike Unix mv, Nash’s implementation only accepts a single source file. To move multiple files, use a loop or script.

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Differences from Unix mv

FeatureUnix mvNash mv
Rename file✅ Supported✅ Supported
Move to directory✅ Supported✅ Supported
Move directory✅ Supported✅ Supported
Multiple sources✅ Supported❌ Single source only
-i (interactive)✅ Supported❌ Not supported
-v (verbose)✅ Supported❌ Not supported
-n (no-clobber)✅ Supported❌ Not supported
-f (force)✅ Supported❌ Not applicable
Cross-filesystemCopies then deletesAlways in-memory

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Use Cases

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Rename for clarity

mv tmp.txt final_report.txt

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Organize downloads

mkdir -p ~/Documents/PDFs
mv *.pdf ~/Documents/PDFs/

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Restructure project

mkdir -p src/lib src/bin
mv *.rs src/lib/
mv main.rs src/bin/

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Atomic file updates

# Write to temp, then atomically replace
echo "new config" > config.json.tmp
mv config.json.tmp config.json

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Move from mounted directory

# Launch Nash with: nash --bind ./uploads:/uploads
mv /uploads/new_file.txt /home/user/processed/

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Common Patterns

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Backup and replace

mv important.txt important.txt.old
cp new_version.txt important.txt

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Clean up after processing

cat input.txt | grep ERROR > errors.txt
mv input.txt processed/

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Batch rename with loop

for file in *.log; do
  mv "$file" "archived_$file"
done
  • cp - Copy files (source remains)
  • rm - Remove files
  • ls - List directory contents
  • mkdir - Create directories
  • stat - Check file information

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