All that is needed are angle brackets.
All that are needed is angle brackets.
For some reason the first sounds better to my ears. Any help on why (or how I am wrong) is appreciated.
All that is needed are angle brackets.
All that are needed is angle brackets.
For some reason the first sounds better to my ears. Any help on why (or how I am wrong) is appreciated.
Regardless of correctness there is an apparent disagreement.
All (that is needed) are angle brackets. (discordance=disagreement)
All (that are needed) is angle brackets. (discordance=disagreement)
※ "All" can be used as singular or plural. It depends on how it is used with other words.
singular
All is lost.
All is calm tonight. All is still. All is OK.
That's all .
All 's well that ends well. (=All that ends well is well : agreement)
[together with fused/relative clause]
All I want is money.(All that I want)
All is not gold that glitters.(=All that glitters is not gold)
All we can do is to wait for him.(All that we can do)
All of the milk is spilt.
All I want is peace and quiet.
All that's fair must fade.(All that is fair)
All that is ancient is beautiful.
plural
All were happy. (Everybody was happy:informal)
All are agreed.
All are welcome.
We all have to go. = All of us have to go. = We all of us have to go.
Now your question.
All that is needed is angle brackets. All that are needed are angle brackets.
My answer When "all" is used in front of a sentence as a pronoun, as things(not people), and as an antecedent, "singular" is better.
I would write like this : All that is needed is a pair of bracket.(if you don't like brackets)