File rename operation in UNIX: Which command is used to rename a file (and can also move it between directories)?

Introduction / Context:
In UNIX/Linux, file manipulation is performed by a small set of powerful commands. Renaming a file is conceptually the same as moving it within the same filesystem to a new name. The mv utility handles both rename and move actions.

Given Data / Assumptions:

• You need to rename a file within the same directory or move it to a different directory.
• There are no filesystem permission issues preventing rename/move.
• No special DOS/Windows commands are available (pure UNIX environment).

Concept / Approach:

mv old new renames a file to a new name in the same directory. mv file dir/ moves a file to another directory, optionally changing the name (dir/new). Unlike copy, mv does not duplicate data; it updates directory entries. Across filesystems, mv effectively performs a copy-and-remove under the hood.

Step-by-Step Solution:

Verification / Alternative check:

Run ls or stat on the destination path to confirm the new name and location. When moving large files across filesystems, monitor disk usage to verify the copy-and-remove succeeded.

Why Other Options Are Wrong:

a: ren is a DOS/Windows command, not standard on UNIX.

c: remove is not the UNIX command (rm deletes files).

d: change is not a UNIX file utility.

e: Not applicable because mv is correct.

Common Pitfalls:

Overwriting existing files without -i; moving across filesystems unexpectedly (which can be slow); attempting to rename files without proper write permissions on the directory.

Final Answer:

mv