Executable files of Linux OS

In Linux, executable files are those that can be run as programs. Unlike Windows, which relies on file extensions like ".exe" to identify executables, Linux uses a different approach.

Here's a breakdown of how executables work in Linux:

1. File Permissions:

• Every file in Linux has associated permissions that determine who can read, write, and execute the file.
• These permissions are set for three user categories:
  • Owner: The user who created the file.
  • Group: The group the file is associated with.
  • Others: Everyone else on the system.
• To make a file executable, you need to set the execute bit for the desired user category (or all three categories). This is usually done using the chmod command in the terminal.

2. File Formats:

• While not a definitive indicator, executable files in Linux often come in the ELF (Executable and Linkable Format) format.
• This is similar to how Windows uses the PE (Portable Executable) format for its executables.
• However, unlike Windows, the file extension doesn't necessarily tell you if a file is executable.

3. Shell Scripts:

• Many Linux programs are actually shell scripts, which are plain text files containing a sequence of commands.
• These scripts have a shebang line at the beginning, specifying the interpreter to use for execution (e.g., #!/bin/bash).
• By default, shell scripts are not executable, and you need to set the execute bit to run them.

4. Running Executables:

• Once a file has the appropriate permissions, you can execute it by:
  • Typing its filename directly in the terminal followed by any arguments.
  • Using the ./ prefix before the filename to indicate the file is in the current directory.

Key Points:

• File extensions are not the primary way to identify executables in Linux.
• Permissions control which users can execute a file.
• Popular executable formats include ELF and shell scripts.
• You can use the chmod command to manage file permissions.