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I am new to Ubuntu and some little thing started bugging me. When I try to install a program, Ubuntu asks:

Do you want to continue[Y/n]?

What is bugging me is why the letter Y is upper case and n is lower case. Whatever case I enter it doesn't change the outcome: it either continues or not.

Do they have any significant reason why one is upper and the latter is lower? Are they trying to notify us that we can enter both and it won't change anything?

2 Answers 2

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Usually, the uppercase option (Y in your case) is the default option if you don't provide any and just press ↲ Enter. This is a convention I see very often on the command line.

I wish I could provide a credible source, but I fail to find one. However, this is something I see very often in Debian/Ubuntu systems, in various programs.

The closest "source" I could find is a Q&A on Stack Overflow: Standard format for yes/no questions in the terminal?

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  • Is there any possible way to change the default option into "N" to make it safer?
    – rebuked
    Jul 22, 2013 at 7:30
  • @rebuked I'm afraid this is a choice made by a developer and unless he provides a way to configure this, you will not be able to change this.
    – gertvdijk
    Jul 22, 2013 at 8:34
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Many Unix/Linux terminal programs do not support even bold or colored text and so conventions like this are used to distinguish the default value if you just pressed ENTER without any text (because it's faster).

Most (well written) programs will accept either upper or lowercase responses (i.e. 'Y','y','N', or 'n').

A lot of these programs are shell scripts so changing the default for a prompt like this is usually not difficult.

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  • 2
    Through some interfaces, terminal programs still do not support color/bold. Sometimes it is correct not to support them. For example, if the user redirects the output of a program to a text file, should that file contain escape characters specifying color codes when the program is run? (The matter is further complicated when a program must be compatible with systems that don't use Unix-style escape codes for color formatting. Some systems, like Windows, have no such escape codes, so color data would be lost in redirection.) Thus, this is applicable beyond tradition and backward compatibility. Jul 24, 2013 at 6:16

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