よりほかない details

write + there is nothing for it but to do

kaku yori hoka nai

there is nothing for it but to do; no course is left but

meaning: have no option but to write

終電しゅうでんがもうないので、歩くあるくよりほかない。

shuuden ga mou nai node, aruku yori hoka nai.

The last train has gone, so I have no option but to walk. neutral

こうなったら、もう待まつほかないね。

kou nattara, mou matsu hoka nai ne.

Now it's come to this, there's nothing to do but wait. casual

Examples

there is nothing for it but to do X — every alternative has been ruled out, so one course remains

終電しゅうでんがもうないので、歩あるくよりほかない。

shuuden ga mou nai node, arukuyorihokanai.

The last train has gone, so I have no option but to walk. neutral

こうなったら、もう待まつほかないね。

kou nattara, mou matsu hoka nai ne.

Now it's come to this, there's nothing to do but wait. casual

相手あいてが譲ゆずらない以上いじょう、こちらが折おれるよりほかはない。

aite ga yuzuranai ijou, kochira ga oreru yori hoka wa nai.

Given that the other side will not budge, it falls to us to give ground. neutral

供給きょうきゅうが回復かいふくしない以上いじょう、価格かかくの改定かいていをお願ねがいするよりほかありません。

kyoukyuu ga kaifuku shinai ijou, kakaku no kaitei o onegai suru yori hoka arimasen.

So long as supply does not recover, we have no recourse but to ask for a price revision. formal

よりほかはない — は inserted for weight; the standard shape in written argument and public statements.
ほかない — より dropped — 待まつほかない. The one shape of the family that turns up in ordinary speech.
よりしかたがない — ほか swapped for 仕方しかた; warmer and more resigned, and the likelier choice when the speaker is complaining — but the より frame keeps it as written as よりほかない, unlike the ほかない row above.

ざるを得ない
ざるを得ない concedes that circumstances have forced an unwilling speaker's hand; よりほかない reports that the alternatives were counted and none survived — it answers "what else is there?", not "must I?".
しか〜ない
Same arithmetic of elimination at opposite registers — しか〜ない is the everyday form and is at home in conversation, while よりほかない is written-formal enough that saying it aloud sounds like reading from a press release.
以外
以外にない and よりほかない both close off every alternative to leave one thing standing, but 以外にない reads as a plain list with one item excluded (これ以外にない), while よりほかない reads as options ruled out one by one until nothing else survives — the first is arithmetic, the second is resignation.

より
The より here is not the comparative — 歩あるくよりほかない says walking is all that is left, not that walking beats something else, and the giveaway is that no second item is ever named.