Veja se isso ajuda: Como digitar o grego, o grego politônico no Linux
Trecho:
Result Key combination Works for…
Tonos/Acute ΄ Dead key (;) + vowel All vowels: ά έ ή ί ύ ό ώ
Dialytika ¨ Dead key (:) + vowel These vowels: ϊ ϋ
Dialytika with Tonos Dead key (;) + Dead key (:) + vowel These vowels: ΐ ΰ
Dialytika with Tonos Dead key (:) + Dead key (;) + vowel These vowels ΐ ΰ
Περισπωμένη ῀ AltGr + Dead key ([) + vowel ᾶ ῆ ῖ ῦ ῶ
Υπογεγραμμένη AltGr + Dead key (]) + vowel ᾳ ῃ ῳ
Ψιλή ᾿ AltGr+ Dead key (:) + vowel or ἀ ἐ ἠ ἰ ὐ ὀ ὠ ῤ
the letter ρ
Δασεία ῾ AltGr+ Dead key (”) + vowel or ἁ ἑ ἡ ἱ ὑ ὁ ὡ ῥ
the letter ρ
Βαρεία ` AltGr+ Dead key (’) + vowel ὰ ὲ ὴ ὶ ὺ ὸ ὼ
Μακρόν ¯ AltGr+ Dead key ({) + vowel ᾱ ῑ ῡ
Βραχύ ˘ AltGr+ Dead key (}) + vowel ᾰ ῐ ῠ