meaning of ~てやる

Question

does ~てやる work the same way as ~てあげる does?

does ~てやる have any other meanings?

Answer 1

~てやる is synonymous with ~てあげる but used when the subject of the act (not the person being spoken to) is an inferior. You might define やる as "give or do to an inferior".

So "feed the cat" would be 猫にえさをやる

If your boss told you that your underling needs "a talking to" about something, you might say 私が言ってやります。

Answer 2

I think that the other answers have already outlined the main differences between the two. ～てやる can be much less polite than ～てあげる, but both have the same basic meaning.

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In the book 問題な日本語 by 北{きた}原{はら}保{やす}雄{お}, it's stated that expressions like 猫に[餌]{えさ}をあげる and 花に水をあげる have become frequently used even by the older generation in recent times, even though some people have an uncomfortable feeling when they're said.

It says that essentially, あげる was the 謙{けん}譲{じょう}語{ご} ("humble language") of やる. As a result, expressions like 先生にあげる ("give to a teacher") and 友達にあげる ("give to a friend") have been pointed out as correct, and expressions like 猫に餌をあげる ("feed a cat") and 花に水をあげる ("water a flower") have also been pointed out as incorrect by some people. However, due to shifts in the language, people have started using あげる in places where やる was used, as やる has connotations of 品がない ("lacking style") and 粗野 ("vulgar/rustic/rude") and あげる is a 上品な言い方 ("polite/elegant/gracious way of talking").

It also states that あげる has lost almost all it's humility and has largely changed from being 謙譲語 into 美{び}化{か}語{ご}, and that there is major trend to it only being used for people of equal or lower status. As a result, most students can't say things like これをあげます and カバンを持ってあげます to teachers. It also makes a hypothesis that as 差{さ}し上{あ}げる has come into more common usage, 差し上げる might have replaced the 謙譲語 usage of あげる.

Answer 3

～てやる works the same way ～てあげる does but this is really for inferior ranked people, pets or really close people.

You can use it in the same cases you can use お前. It can be really rude if misused so my best advice would be to avoid using it till you feel confortable enough in japanese.