To answer the question, "Have a nice day" is not something most Irish people would say in Irish Gaelic. That's an American phrase. A phrase like ádh mór! (= good luck - used mostly in Ulster Irish) and maybe tóg(a'í) go réidh é! (= take it easy - used quite often in Connemara) might be what Irish-speaking people would say in such circumstances. Or you could try "Tá súil agam go mbeidh lá breá agat" which means
"I'm hoping you will have a fine day''
Slán agus beannacht leat
(literally: goodby and blessing to you)
'Lá ar dóigh agat' is the Irish for 'Have a great day'.
In Irish it's: Lá ar dóigh agat (singular) / Lá ar dóigh agaibh (plural)
In Scottish Gaelic: Latha math agaibh.
Most people in Ireland speak English so you would just say "Have a good day." In the Irish language you would say "Lá maith agat." That would be pronounced: Law mot agut.
Tá súil agam go mbeidh lá ar dóigh agat
Bíodh an-lá agat.
In Irish it's "laethanta sona"
'Of the day' is an Lae in the Irish language.It's an Latha in (Scottish) Gaelic.
In Irish Gaelic as a greeting, Dia dhuit! On taking leave Lá maith agat!In the sense of 'a good day' it's Lá maith.In Scots Gaelic latha math or latha bréagha.
Irish (Gaelic): lá Scottish Gaelic: lathaLá, pronounced like law.
In Irish, 'the common good' would be 'leas an phobail'.In Scottish Gaelic: ?
maithmaith
In Irish Gaelic: slán leat (slán libh. plural)
go mhaith
In Irish it's "bia maith, sláinte mhaith"
irish: focal an lae
In Irish: leasdeirfiúr. In Scottish Gaelic: leas-phiuthar
Scottish Gaelic, Irish Gaelic, and Manx all derive from Old Irish.