Multiple choice technology operating systems

Which one of the following is the syntax for a pattern that matches the null string or a filename beginning with a or A

  1. ?([A-a].*)

  2. ?([aA]*)

  3. ?([aA].*)
  4. ?([aA]$)
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B Correct answer
Explanation

In shell globbing with extended patterns, ?([aA]*) matches zero or one occurrences of a string starting with 'a' or 'A' followed by any characters, which effectively matches the null string or filenames beginning with 'a' or 'A'.

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