Recently I was asked to translate an imperative phrase "don’t fail (to do it)"

Ná teip ort é a dhéanamh
Ná teipeadh ort é a dhéanamh

?

It's only a suggestion on my part - déan/déanaigí é sin gan teip
In the dictionary - to fail to do something - is - faillí a thabhairt i ndéanamh ruda.

Interesting, I see the difficulty. My first inclination would the second one in the third person, but I'm not totally sure why.

You could sidestep the issue by using loic, I think.

Ná loic é a dhéanamh.

But that's not the question.

I think because "é a dhéanamh" is grammatically the subject of the sentence, and "tú" in "ort" only a logical subject.
Though I have no problems with 3rd person commands like: "Ná bíodh eagla ort", I am reluctant here to give a command to a verbal noun phrase
Unfortunately I didn't find any examples for an imperative with "teip ar" in Irish, so perhaps no one would use this verb in imperative mood.

And that’s why ...


... this is a good idea.

Including a subject in an imperative sentence is weird, whatever the subject. If it's acceptable with "eagal", I'd be inclined to assume that's an exception.

Incidentally, Scottish Gaelic uses "take" for state nouns in negative imperative, eg "na gabh eagal". Is there a similar construction in Irish?

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A language belongs to its native speakers, and when you speak it, you are a guest in their homes.
If you are not a good guest, you have no right to complain about receiving poor hospitality.

Not that I'm aware of. FGB translates "Don't be afraid" as Ná bíodh eagla ort and things like "Have a good day" are Bíodh lá maith a'd.

Ah, so Irish has done the same thing as English and allowed many subjunctive forms to fall together with imperatives. ScG preserves subjunctives in eg "gum bi là math agad", because this is essentially a subordinate second clause: "(I hope that you) have a nice day." "Don't be afraid" and "don't worry" are true imperatives, so use a different structure ("na gabh dragh", "na gabh eagal").

_________________
A language belongs to its native speakers, and when you speak it, you are a guest in their homes.
If you are not a good guest, you have no right to complain about receiving poor hospitality.

Perhaps Gaelic was under French influence here (as Scottish culture was for quite a while). The French do the same thing with expressions like "Qu'il entre!", meaning "Let him enter!", but literally being the subordinate clause in "[I order] that he enter".

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I'm not a native (or entirely fluent) speaker, so be sure to wait for confirmations/corrections, especially for tattoos.

Pretty much every Indo-European language that still has a subjunctive does this - English used to, before it lost it. Even Irish used to do it - "gura maith agat" is the same structure of subjunctive as a wish or blessing.

_________________
A language belongs to its native speakers, and when you speak it, you are a guest in their homes.
If you are not a good guest, you have no right to complain about receiving poor hospitality.