C is Ans
mkdir PIS PIS/progs PIS/data
Creates PIS parent directory first then inside that two sub directories namely progs and data are created.
But I would do like this to get the same effect:-
mkdir -p PIS /{progs,data}
The above creates the top-level directory PIS, along with all of the subdirectories PIS/progs,PIS/data,).
How does it work? There are two things of note about the command above:
The -p flag: This tells mkdir to create any leading directories that do not already exist. Effectively, it makes sure that PIS gets created before creating PIS/progs.
The {} lists: The technical name for these is "brace expansion lists". Basically, the shell interprets this as a list of items that should be appended individually to the preceding path. Thus, a/{b,c} is expanded into a/b a/c.