File Operations

OpenSandbox provides comprehensive file operation capabilities, allowing you to read, write, and manipulate files within sandbox environments. This guide covers essential file operations with practical examples.

Overview

The File Operations API enables:

Writing files: Create files with specific content and permissions
Reading files: Retrieve file contents as text or binary data
Directory operations: List, create, and navigate directories
File metadata: Access file permissions, sizes, and timestamps
Batch operations: Write multiple files in a single operation

Basic File Operations

Setup

Import the required modules and create a sandbox:

import asyncio
from datetime import timedelta

from opensandbox import Sandbox
from opensandbox.models import WriteEntry

async def main() -> None:
    sandbox = await Sandbox.create(
        "opensandbox/code-interpreter:v1.0.1",
        entrypoint=["/opt/opensandbox/code-interpreter.sh"],
        timeout=timedelta(minutes=10),
    )

    async with sandbox:
        # File operations go here
        pass

    await sandbox.kill()

Write a single file

Create a file with text content:

        # Write a text file
        await sandbox.files.write_files([
            WriteEntry(
                path="/tmp/hello.txt",
                data="Hello OpenSandbox!",
                mode=644  # rw-r--r--
            )
        ])

        print("File written successfully")

The WriteEntry model accepts:

path: Absolute file path in the sandbox
data: File content as string or bytes
mode: Unix file permissions (e.g., 644, 755)

Read a file

Retrieve file contents:

        # Read the file
        content = await sandbox.files.read_file("/tmp/hello.txt")
        print(f"File content: {content}")
        # Output: File content: Hello OpenSandbox!

Write multiple files

Create several files in one operation:

        # Write multiple files at once
        files_to_write = [
            WriteEntry(
                path="/tmp/config.json",
                data='{"version": "1.0", "enabled": true}',
                mode=644
            ),
            WriteEntry(
                path="/tmp/script.sh",
                data="#!/bin/bash\necho 'Script running'\n",
                mode=755  # rwxr-xr-x (executable)
            ),
            WriteEntry(
                path="/tmp/data.txt",
                data="Sample data\nLine 2\nLine 3",
                mode=644
            ),
        ]

        await sandbox.files.write_files(files_to_write)
        print(f"Successfully wrote {len(files_to_write)} files")

List directory contents

Use shell commands to explore directories:

        # List files in /tmp
        result = await sandbox.commands.run("ls -lh /tmp")
        print("Directory contents:")
        for line in result.logs.stdout:
            print(line.text)

Output:

Directory contents:
-rw-r--r-- 1 user user   41 Mar 01 10:30 config.json
-rw-r--r-- 1 user user   25 Mar 01 10:30 data.txt
-rw-r--r-- 1 user user   19 Mar 01 10:30 hello.txt
-rwxr-xr-x 1 user user   35 Mar 01 10:30 script.sh

Read and verify files

Read back the files to verify content:

        # Read JSON config
        config = await sandbox.files.read_file("/tmp/config.json")
        print(f"Config: {config}")
        # Output: Config: {"version": "1.0", "enabled": true}

        # Read script
        script = await sandbox.files.read_file("/tmp/script.sh")
        print(f"Script: {script}")
        # Output: Script: #!/bin/bash\necho 'Script running'

        # Execute the script
        exec_result = await sandbox.commands.run("bash /tmp/script.sh")
        print(f"Script output: {exec_result.logs.stdout[0].text}")
        # Output: Script output: Script running

Advanced File Operations

Working with Binary Files

Write and read binary data:

import base64

# Create binary data (example: small PNG)
binary_data = base64.b64decode(
    "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg=="
)

# Write binary file
await sandbox.files.write_files([
    WriteEntry(
        path="/tmp/image.png",
        data=binary_data,
        mode=644
    )
])

# Verify file was written
result = await sandbox.commands.run("file /tmp/image.png")
print(result.logs.stdout[0].text)
# Output: /tmp/image.png: PNG image data, 1 x 1, 8-bit/color RGBA

Creating Directory Structures

# Create nested directories
await sandbox.commands.run("mkdir -p /tmp/project/src /tmp/project/tests")

# Write files into directory structure
project_files = [
    WriteEntry(
        path="/tmp/project/README.md",
        data="# My Project\n\nProject documentation here.",
        mode=644
    ),
    WriteEntry(
        path="/tmp/project/src/main.py",
        data="def main():\n    print('Hello World')\n\nif __name__ == '__main__':\n    main()",
        mode=644
    ),
    WriteEntry(
        path="/tmp/project/tests/test_main.py",
        data="import unittest\n\nclass TestMain(unittest.TestCase):\n    def test_example(self):\n        self.assertTrue(True)",
        mode=644
    ),
]

await sandbox.files.write_files(project_files)

# Verify structure
tree_result = await sandbox.commands.run("find /tmp/project -type f")
for line in tree_result.logs.stdout:
    print(line.text)

File Permissions and Metadata

# Create file with specific permissions
await sandbox.files.write_files([
    WriteEntry(
        path="/tmp/executable.sh",
        data="#!/bin/bash\necho 'Running...'",
        mode=755  # Owner: rwx, Group: rx, Others: rx
    )
])

# Check permissions
perms = await sandbox.commands.run("ls -l /tmp/executable.sh")
print(perms.logs.stdout[0].text)
# Output: -rwxr-xr-x 1 user user 31 Mar 01 10:30 /tmp/executable.sh

# Execute the file
result = await sandbox.commands.run("/tmp/executable.sh")
print(result.logs.stdout[0].text)
# Output: Running...

Complete Working Example

import asyncio
from datetime import timedelta

from opensandbox import Sandbox
from opensandbox.models import WriteEntry


async def main() -> None:
    # Create sandbox
    sandbox = await Sandbox.create(
        "opensandbox/code-interpreter:v1.0.1",
        entrypoint=["/opt/opensandbox/code-interpreter.sh"],
        timeout=timedelta(minutes=10),
    )

    async with sandbox:
        print("=== File Operations Demo ===")

        # 1. Write multiple files
        print("\n1. Writing files...")
        await sandbox.files.write_files([
            WriteEntry(
                path="/tmp/hello.txt",
                data="Hello OpenSandbox!",
                mode=644
            ),
            WriteEntry(
                path="/tmp/config.json",
                data='{"version": "1.0", "enabled": true}',
                mode=644
            ),
            WriteEntry(
                path="/tmp/script.sh",
                data="#!/bin/bash\necho 'Script is running'\n",
                mode=755
            ),
        ])
        print("Files written successfully")

        # 2. List directory contents
        print("\n2. Directory contents:")
        ls_result = await sandbox.commands.run("ls -lh /tmp/*.{txt,json,sh}")
        for line in ls_result.logs.stdout:
            print(f"  {line.text}")

        # 3. Read files
        print("\n3. Reading files:")
        hello_content = await sandbox.files.read_file("/tmp/hello.txt")
        print(f"  hello.txt: {hello_content}")

        config_content = await sandbox.files.read_file("/tmp/config.json")
        print(f"  config.json: {config_content}")

        # 4. Execute script
        print("\n4. Executing script:")
        exec_result = await sandbox.commands.run("bash /tmp/script.sh")
        print(f"  Output: {exec_result.logs.stdout[0].text}")

        # 5. Create directory structure
        print("\n5. Creating project structure:")
        await sandbox.commands.run("mkdir -p /tmp/myapp/src")
        await sandbox.files.write_files([
            WriteEntry(
                path="/tmp/myapp/README.md",
                data="# My Application\n\nBuilt with OpenSandbox",
                mode=644
            ),
            WriteEntry(
                path="/tmp/myapp/src/app.py",
                data="print('Application started')",
                mode=644
            ),
        ])

        tree_result = await sandbox.commands.run("find /tmp/myapp -type f")
        print("  Project files:")
        for line in tree_result.logs.stdout:
            print(f"    {line.text}")

    # Cleanup
    await sandbox.kill()
    print("\n=== Demo completed ===")


if __name__ == "__main__":
    asyncio.run(main())

Expected Output

=== File Operations Demo ===

1. Writing files...
Files written successfully

2. Directory contents:
  -rw-r--r-- 1 user user 41 Mar 01 10:30 /tmp/config.json
  -rw-r--r-- 1 user user 19 Mar 01 10:30 /tmp/hello.txt
  -rwxr-xr-x 1 user user 35 Mar 01 10:30 /tmp/script.sh

3. Reading files:
  hello.txt: Hello OpenSandbox!
  config.json: {"version": "1.0", "enabled": true}

4. Executing script:
  Output: Script is running

5. Creating project structure:
  Project files:
    /tmp/myapp/README.md
    /tmp/myapp/src/app.py

=== Demo completed ===

Best Practices

Use appropriate file permissions

Use 644 (rw-r—r—) for data files
Use 755 (rwxr-xr-x) for executable scripts
Use 600 (rw-------) for sensitive files

Batch write operations

When writing multiple files, use a single write_files() call instead of multiple individual writes for better performance.

Handle file paths correctly

Always use absolute paths in the sandbox. The working directory may vary depending on the image configuration.

Verify file operations

After critical file operations, use shell commands to verify files were created correctly:

# Check if file exists
result = await sandbox.commands.run("test -f /tmp/myfile.txt && echo 'exists' || echo 'missing'")

Common Use Cases

Configuration Files

Write configuration files before running applications:

await sandbox.files.write_files([
    WriteEntry(
        path="/app/config.yaml",
        data="""database:
  host: localhost
  port: 5432
logging:
  level: INFO""",
        mode=644
    )
])

Data Processing

Write input data, process it, and read results:

# Write input data
await sandbox.files.write_files([
    WriteEntry(path="/data/input.csv", data="name,age\nAlice,30\nBob,25", mode=644)
])

# Process with Python
await sandbox.commands.run(
    "python -c \"import csv; "
    "data = list(csv.DictReader(open('/data/input.csv'))); "
    "avg = sum(int(r['age']) for r in data) / len(data); "
    "print(f'Average age: {avg}')\""
)

# Read results
result = await sandbox.files.read_file("/data/output.txt")

Next Steps

Basic Sandbox

Go back to basic sandbox operations

Code Interpreter

Learn code execution capabilities

AIO Sandbox

Explore All-in-One sandbox with browser automation

API Reference

Complete file operations API documentation

Getting Started

AI Coding Agents

Browser & Desktop

Advanced

Overview

Basic File Operations

Advanced File Operations

Working with Binary Files

Creating Directory Structures

File Permissions and Metadata

Complete Working Example

Expected Output

Best Practices

Common Use Cases

Configuration Files

Data Processing

Next Steps

Basic Sandbox

Code Interpreter

AIO Sandbox

API Reference

Build docs developers (and LLMs) love

Getting Started

AI Coding Agents

Browser & Desktop

Advanced

​Overview

​Basic File Operations

​Advanced File Operations

​Working with Binary Files

​Creating Directory Structures

​File Permissions and Metadata

​Complete Working Example

​Expected Output

​Best Practices

​Common Use Cases

​Configuration Files

​Data Processing

​Next Steps

Basic Sandbox

Code Interpreter

AIO Sandbox

API Reference

Build docs developers (and LLMs) love

Overview

Basic File Operations

Advanced File Operations

Working with Binary Files

Creating Directory Structures

File Permissions and Metadata

Complete Working Example

Expected Output

Best Practices

Common Use Cases

Configuration Files

Data Processing

Next Steps