Intro to Unix / Linux cd to the /etc directory. Execute the following command. l

Question

Intro to Unix / Linux

cd to the /etc directory.

Execute the following command.

ls -l au*.[mn]*

The output is the following:

-rw-r--r-- 1 root root 675 Jan 24 19:04 auto.master

-rw-r--r-- 1 root root 524 Mar 22 2012 auto.misc

-rwxr-xr-x 1 root root 1374 Mar 22 2012 auto.net

This is exactly the output I was hoping for.

What function are the [ ] performing?

A.) They look good and balance the command string.

B.) The uniquely match the m and n characters to ensure only the desired output os generated.

C.) They neutralize the m and n characters to hide the output

D.) They were used by mistake and have no meaning.

Explanation / Answer

Ans: B)

Consider an example that a directory named "etc" and there are lots of files in it.

Suppose the expression to list the files a.txt and b.txt would be ls -l [ab].txt:

So this will serach for a.txt and b.txt in the file list.

Here its [mn]* which means it starts with m and wild card * or with n and wild card *.

The wildcard * suggests anything.

So the whole expression ls -l au*.[mn]* Which means name starts with au and any wildcard before "." and [mn]* means starting with m or n and follwed by any wild card

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