Linux Foundation Exam LFCS Topic 2 Question 53 Discussion

Actual exam question for Linux Foundation's LFCS exam

Question #: 53
Topic #: 2

[All LFCS Questions]

When running the command

sed -e "s/a/b/" /tmp/file >/tmp/file

While /tmp/file contains data, why is /tmp/file empty afterwards?

AThe file order is incorrect. The destination file must be mentioned before the command to ensure redirection.

BThe command sed did not match anything in that file therefore the output is empty.

CWhen the shell establishes the redirection it overwrites the target file before the redirected command starts and opens it for reading.

DRedirection for shell commands do not work using the > character. It only works using the | character instead.

Show Suggested Answer

Suggested Answer: D

by Refugia at Feb 06, 2023, 02:47 PM

Limited Time Offer

25%

Off

Get Premium LFCS Questions as Interactive Web-Based Practice Test or PDF

Contribute your Thoughts:

Submit Cancel

Clorinda

2 hours ago

I'm going with option C on this one. The shell is like a ninja, silently overwriting the target file before the command even has a chance to do its thing. Sneaky, but that's how it works.

upvoted 0 times

...

Alesia

14 days ago

Hmm, that makes sense too. Maybe we should review how sed works before the exam.

upvoted 0 times

...

Hmm, let's see... the file order is definitely not the issue here. And the sed command seems to be working fine, so it's not that either. Aha, I bet it's that sneaky overwrite that happens before the redirection kicks in! Gotta love those shell quirks.

upvoted 0 times

...

Julieta

16 days ago

I disagree, I believe the answer is B. The sed command did not match anything in the file.

upvoted 0 times

...

Lewis

17 days ago

Whoa, talk about a classic shell command conundrum! I bet the folks who write these certification exams just love tripping us up with little gotchas like this.

upvoted 0 times

Janet

1 days ago

C) When the shell establishes the redirection it overwrites the target file before the redirected command starts and opens it for reading.

upvoted 0 times

...

Eliz

2 days ago

B) The command sed did not match anything in that file therefore the output is empty.

upvoted 0 times

...

Josefa

6 days ago

A) The file order is incorrect. The destination file must be mentioned before the command to ensure redirection.

upvoted 0 times

...

Alesia

26 days ago

I think the answer is C. The shell overwrites the target file before the command starts.

upvoted 0 times

...

Linux Foundation Exam LFCS Topic 2 Question 53 Discussion

Contribute your Thoughts:

Clorinda

Alesia

Amber

Julieta

Lewis

Janet

Eliz

Josefa

Alesia