Press SPACE to continue (not ENTER)

Question

I know this question has been already asked & answered, but the solution I found listens for space and enter:

while [ "$key" != '' ]; do
        read -n1 -s -r key
done

Is there a way (in bash) to make a script that will wait only for the space bar?

what should it do when the users hits some other key? (not if, when.) — ilkkachu, Oct 18, 2020 at 15:41

Cyrus · Accepted Answer · 2020-10-17 07:17:49Z

21

I suggest to use only read -d ' ' key.

-d delim: continue until the first character of DELIM is read, rather than newline

See: help read

answered Oct 17, 2020 at 7:17

Cyrus

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1

Wow! Thank you. This is what I was looking for. @OskarSkog If you mean if it'll show what you're typing, then yes, this will show the keys you're pressing in the terminal, but you can disable it by adding -s flag, like read -s -d ' ' (you don't need the key variable here, if you only want it to wait for the space key)
– adazem009
Oct 17, 2020 at 7:54
@adazem009 No, I was asking about buffering not echoing. The man page for bash's read doesn't clearly mention it but it obviously works without waiting for a line feed.
– Oskar Skog
Oct 17, 2020 at 9:28
1

@adazem009 On the negative side of things, read is painfully inefficient: it makes a system call for each character it reads (which is kind of why it can do this trick of reading a space without needing Enter). For more reasons to avoid using read unless you have no other option, please see Stéphane's excellent answer here: unix.stackexchange.com/q/169716/88378
– PM 2Ring
Oct 18, 2020 at 14:39

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