File Operations

File Operations Skill

Perform file system operations and manage files and directories.

When to Use

Use this skill when the user wants to:

• Read/write files
• Manage directories and files
• Process file contents
• Handle file uploads/downloads
• Implement file watching
• Work with file metadata
• Process multiple files
• Handle file errors gracefully

File Reading

Reading Files

// Node.js
const fs = require('fs');
fs.readFile('file.txt', 'utf8', (err, data) => {
  if (err) throw err;
  console.log(data);
});

# Python
with open('file.txt', 'r') as f:
    data = f.read()

Reading Line by Line

# Shell
while IFS= read -r line; do
  echo "$line"
done < input.txt

# Python
with open('input.txt', 'r') as f:
    for line in f:
        process(line)

File Writing

Writing Files

// Node.js
fs.writeFile('output.txt', 'Hello World', (err) => {
  if (err) throw err;
});

# Python
with open('output.txt', 'w') as f:
    f.write('Hello World')

Appending to Files

// Node.js
fs.appendFile('log.txt', 'Error: Something went wrong\n', (err) => {
  if (err) throw err;
});

# Python
with open('log.txt', 'a') as f:
    f.write('Error: Something went wrong\n')

Directory Operations

Directory Creation

# Create directory
mkdir -p project/src

# Create recursive directories
mkdir -p parent/child/grandchild

// Node.js
fs.mkdirSync('project', { recursive: true });
fs.mkdir('project/src', { recursive: true }, (err) => {
  if (err) throw err;
});

Directory Listing

# List files
ls -la

# List recursively
find . -type f

# List with details
ls -lh

Directory Removal

# Remove directory (empty)
rmdir empty_dir

# Remove recursively (force)
rm -rf directory

# Remove non-empty directory
rm -rf directory/

File Metadata

File Information

# Get file details
ls -lh file.txt
stat file.txt

# Get file size
wc -l file.txt
du -h file.txt

// Node.js
fs.stat('file.txt', (err, stats) => {
  console.log(stats.size);      // Size in bytes
  console.log(stats.mtime);     // Last modified time
  console.log(stats.isDirectory()); // Is directory?
});

File Types

# Check file type
file file.txt

# Check if exists
test -f file.txt
test -d directory

File Processing

Copy Files

# Simple copy
cp source.txt dest.txt

# Recursive copy
cp -r source_dir/ dest_dir/

# Preserve attributes
cp -p source.txt dest.txt

Move/Rename Files

# Rename
mv old.txt new.txt

# Move to directory
mv file.txt directory/

# Move multiple files
mv file1.txt file2.txt destination/

Delete Files

# Delete file
rm file.txt

# Delete non-empty directory
rm -r directory/

# Force delete (no prompts)
rm -f file.txt

# Delete all in directory
rm -rf directory/

Find and Process Files

# Find files by name
find . -name "*.txt"

# Find files by pattern
find . -name "*.log*"

# Find by modification time
find . -mtime -7

Batch Operations

# Process all files in directory
for file in *.txt; do
  process "$file"
done

# Find and process files
find . -type f -name "*.json" -exec ./process.sh {} \;

File Watching

Watch for Changes

// Node.js fs.watch
fs.watch('file.txt', (eventType, filename) => {
  if (eventType === 'change') {
    console.log('File changed:', filename);
  }
});

Directory Watching

// Node.js recursive watch
const watcher = fs.watch('directory', { recursive: true }, (eventType, filename) => {
  console.log(`${eventType}: ${filename}`);
});

File Transfer

Upload Files

// Node.js file upload
const FormData = require('form-data');
const form = new FormData();
form.append('file', fs.createReadStream('document.pdf'));

axios.post('/upload', form, {
  headers: form.getHeaders()
});

Download Files

// Node.js download
fs.download('https://example.com/file.zip', 'output.zip', (err) => {
  if (err) throw err;
});

Error Handling

File Not Found

// Node.js
fs.readFile('missing.txt', (err, data) => {
  if (err) {
    if (err.code === 'ENOENT') {
      console.log('File not found');
    } else {
      console.error('Error reading file:', err);
    }
  }
});

Permission Errors

// Check permissions
try {
  fs.accessSync('protected.txt', fs.constants.R_OK);
  console.log('Read permission granted');
} catch (err) {
  console.log('No permission:', err.code);
}

File Compression

Zip Files

# Create zip
zip archive.zip file1.txt file2.txt

# Add files to zip
zip archive.zip file3.txt

# Recursively zip directory
zip -r archive.zip directory/

Extract Archives

# Extract zip
unzip archive.zip

# Extract to specific directory
unzip archive.zip -d destination/

# Extract without preserving permissions
unzip -a archive.zip

Deliverables

• Complete file operation implementation
• Error handling strategies
• File processing utilities
• Documentation
• Examples

Quality Checklist

• File operations are atomic
• Error handling is comprehensive
• Permissions are checked
• Race conditions are prevented
• Sensitive file operations are secured
• File paths are validated
• Large files are handled properly
• Temporary files are cleaned up