Executable Search Order in DOS When you type a command at the DOS prompt without an extension, in what order does COMMAND.COM search for executable files?

Introduction / Context:
Command resolution is the process the shell uses to find and start the program you request. DOS’s COMMAND.COM follows a consistent search order for extensions when none is specified at the prompt, which affects which file actually runs if multiple variants exist.

Given Data / Assumptions:

• Standard COMMAND.COM behavior.
• PATH variable may direct the search across directories, but the extension priority stays the same.
• Files of the same base name may exist with different extensions in the same directory.

Concept / Approach:
COMMAND.COM first looks for a .COM file, then for a .EXE file, and finally for a .BAT file. This means a tiny .COM utility can shadow an .EXE or .BAT with the same name, leading to different behavior than expected.

Step-by-Step Solution:
User types FOO at the prompt.COMMAND.COM checks for FOO.COM; if present, it runs.If not found, it checks for FOO.EXE; if present, it runs.If neither is found, it checks for FOO.BAT and runs it if available.

Verification / Alternative check:
Create FOO.COM, FOO.EXE, and FOO.BAT in the same directory with distinctive output. Typing FOO will execute FOO.COM first, verifying the order COM → EXE → BAT.

Why Other Options Are Wrong:
Options A, B, and D list orders that contradict DOS’s documented behavior.Option E is incorrect because there is a definitive, standard order.

Common Pitfalls:

• Unexpectedly running a .COM utility when intending to run a .BAT script with the same name.
• Security implications: placing a rogue .COM earlier in PATH can hijack execution.

Final Answer:
COM, EXE, BAT