UNIX file management: Which command removes (deletes) a file from the filesystem, permanently freeing its directory entry and disk space after the last link is gone?

Introduction / Context:
Deleting files is a core administrative skill on UNIX and Linux. Unlike some desktop environments that send files to a recycle bin, the rm command permanently removes directory entries. When no other hard links reference the inode and no process keeps the file open, the space is reclaimed.

Given Data / Assumptions:

• You have a standard POSIX shell environment.
• The task is deleting a file (not moving or renaming).
• Permissions allow deletion (write permission on the parent directory is crucial).

Concept / Approach:

rm removes directory entries for files and directories (with -r for recursive). It does not ask for confirmation by default, so using -i is safer in interactive sessions. The actual data blocks are freed when no references remain, and the kernel updates filesystem metadata accordingly.

Step-by-Step Solution:

Verification / Alternative check:

Run ls or find to confirm the file is gone. If a process had the file open, lsof can show open handles; space is reclaimed once handles close.

Why Other Options Are Wrong:

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

b: mv moves or renames a file; it does not delete it.

d: remove is not the standard user command; rm is.

e: Not applicable because rm is correct.

Common Pitfalls:

Accidental use of wildcards, removing files as root without prompts, and attempting to delete without write permission on the parent directory. Consider aliases like rm -i to add a safety net.

Final Answer:

rm