File

Abstract

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Quote

Linux Kernel is a file based but Windows is an API based.

This just means that in Linux, we can use the same file System Call (系统调用) on IO Device like Special File & Unix Domain Socket besides the regular files, where Windows has an separate Windowa API for those IO Devices.

• Hide the nitty gritty of IO Device, so users can focus on manipulating the content inside the IO Device

• Present programmer a clean Abstraction (抽象) of device-independent file

• Examples are Printers & Modems etc

  
  

• 2 parts - Filename & Inode Number, doesn’t have any metadata associated

Create a dummy file with a specified size

This could be useful for testing the Network Throughput.

def generate_dummy_file(file_path, size_gb):
    with open(file_path, 'wb') as f:
        f.write(b'\0' * (1024 * 1024 * 1024 * size_gb))
 
file_path = input("Enter the name for the dummy file: ") + '.bin'
size_gb = int(input("Enter the size in GB: "))
 
generate_dummy_file(file_path, size_gb)
print(f"Dummy file of size {size_gb}GB generated at '{file_path}'")

File Descriptor

• A small Integer (整数) associated with File

File Permission

• In POSIX, file permissions are handled by rwx bits

Special File

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• An Linux Kernel concept - make IO Device look like File, so we can reuse the same set of file System Call (系统调用) on IO Devices
• By convention, kept in the /dev

Block Special Files

• Model IO Device that has a collection of randomly addressable blocks like like Flash Memory

Character Special Files

• Model IO Device that accept or output a character stream like keyboard

Line Break in File

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• POSIX systems uses a single character called Line Feed \n
• While Windows uses carriage return and Line Feed, so 2 characters \r\n. This is because during typewriter times, you needed to mov the carriage to restart typing on the beginning of a line first, then turn the wheel to move the paper to change the line

Hands-On!

You can install dos2unix and unix2dos using Brew to play with line break.

You can view the hidden line break character by downloading and configuring bat.

Useful CLi Tools

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bat

• A cat clone with wings.

brew install bat && echo "alias cat='bat'" >>~/.zshrc

dua

• Manage files fast, powered by rust!

brew install dua-cli
 
dua interactive

xcp

• cp on tren!

cargo install xcp
# Alias to cp
alias cp="xcp"

xxd

• Generate a hexdump from a binary file and display the output

xxd <BINARY_NAME.bin>