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I am new to Ubuntu and I am trying hard to understand the command line.

When I want to see the contents of a tar file I use:

tar tf tarfile.tar

But when I want to see a listing of all file if I use:

ls a filename

It says:

ls: cannot access a: No such file or directory

Why is that?

Why is the minus sign "-" required for one command and not for the other?

Chirag Bhatia - chirag64
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Dianne
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1 Answers1

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The tar command is one of the oldest commands in *nix. It was created long long ago to do tape archives where data was stored on tape drives.

When the utility was written, the current standard of putting a dash to indicate a parameter was not yet invented.

It is optional for tar, but mandatory for almost every other command.

Marianna
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