UGC NET CSE | December 2015 | Part 3 | Question: 57

Question

What will be the output of the following Unix command?

$\text{\$ rm chap0[1-3]}$

• A.

  Remove file $\text{chap0[1-3]}$

• B.

  Remove file $\text{chap01, chap02, chap03}$

• C.

  Remove file $\text{chap [1-3]}$

• D.

  None of the above

Answer 1

ans is A

Square brackets can surround a choice of single characters (i.e., one digit or one letter) you’d like to match. For example, [Cc]hapterwould match either Chapter or chapter, but [ch]apter would match either capter or hapter. Use a hyphen (-) to separate a range of consecutive characters. For example, chap[1-3] would match chap1,chap2, or chap3.

But if escape sequence(\) is used then it literally matches with that after \

so $rm chap0\[1-3\] will remove 

Remove file chap0[1-3]

 

Comments

what does '\' signify in chap0\ and [1-3\]

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Will it not be option B according to your logic

Answer 2

Escape character in front of the brackets removes their meanings.

 

Hence it just deletes a file named chap0[1-3]