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I saw someone do this to replace "upon" with "eat" in a text file called oro. 

sed -i -e "s|upon|eat|" oro

Question: what is the purpose of -e option in the above command? I tried with and without the -e option and observed no differences.

Tosh
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    @yaegashi - if it is a duplicate, I don't think it should matter - there aren't any answers at that link which answer the question. There are a few which talk about ways to handle it - but not a one which discusses its purpose - especially in the context of `-i`. Ok, there was one - a good one - short and sweet - but not regarding `-i`, – mikeserv Jun 03 '15 at 04:39
  • @mikeserv [This answer](http://unix.stackexchange.com/a/33160/111878) explains it pretty well: you can't have `sed '/foo/i\bar; /fred/a\barny; /harry/c\potter'`, since `i`, `a`, and `c` have to be terminated by newlines. Using `-e` allows you to pass `i`, `a`, and `c` on the command line. `-i` is completely irrelevant to this issue. – lcd047 Jun 03 '15 at 06:18
  • @lcd047 - you're wrong about `-i` - and none of those have to be terminated by newlines either. `-e` does not allow you terminate it with a newline - a newline does that. – mikeserv Jun 03 '15 at 06:21
  • @mikeserv Please try this: `echo foo | sed -e '/foo/a\' -e 'bar'` – lcd047 Jun 03 '15 at 06:26
  • @lcd047 - i know how it works - but it doesn't work with newlines, and they don't need terminating newlines, either. At least, not in this case. There are two ways to terminate those commands portably - one you've just demonstrated, and the other is a newline. Except that's not the only way to do it the way you have just done. – mikeserv Jun 03 '15 at 06:31
  • @lcd047 - maybe [look here](http://unix.stackexchange.com/q/148551/52934). – mikeserv Jun 03 '15 at 06:33
  • @mikeserv My point was to show you why `-e` is needed. `echo foo | sed '/foo/a\bar'` doesn't work, while `echo foo | sed -e '/foo/a\' -e bar` does (with no `-i` in sight, either). I wasn't trying to find all (or any) ways to make `a\ ` work, portable or not. – lcd047 Jun 03 '15 at 06:35
  • @lcd047 - But you didn't. You did as those answers do and talked about *where* it's needed. I know where it's needed - and i also know why. I don't believe you do - and those answers don't discuss it either. It's not a big deal - but you're not helping your case by confirming my complaint. And, yes, i know there was no `-i` in sight, but there is one the question here, and it is not unrelated. – mikeserv Jun 03 '15 at 06:39
  • @mikeserv _I don't believe you do_ - Am I allowed to call you names in response, then? :) _And, yes, i know there was no `-i` in sight, but there is one the question here, and it is not unrelated._ - Then please show how it's related. So far you (1) have rejected my explanation without giving any reason, and (2) started a pissing contest. Surely you can do better than that? – lcd047 Jun 03 '15 at 06:48
  • @lcd047 - I didn't call you any names - I certainly don't discriminate against people based on their understanding of edgecase `sed` parsing rules. And anyway, just that you know *where* it's needed is far more than most, so if I did - and if ever it was in any danger of affecting my opinion of you - it would have *positively* done so. But it didn't - and never would have. Yes, I don't believe you do - I'm sorry if that offends you. But I am done talking with you about it. If you wish to have some answers from my perspective - you can follow the link. Or not. I don't care. – mikeserv Jun 03 '15 at 06:54
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    @mikeserv Ok, so to answer your question _why_: `-e` compiles its arguments as a string (`compile_string()` in GNU `sed` sources), while `-f` and `'...'` compile their argument as a program (`compile_file()` in GNU `sed`). This means `-e` terminates commands, which is why `sed -e '/foo/a\' -e bar` works, and `sed '/foo/a\' -e bar` doesn't. In the original question `-e` doesn't make any difference because `s` doesn't care whether something follows or not. Have a good day, too. – lcd047 Jun 03 '15 at 07:01
  • @lcd047 - Yeah, that is, in a roundabout way, why. The `-e` command is a script - as is `-f` - they can be intermingled. Anyway, GNU writes its sources according to a standard - which is far clearer on the matter. The terminator in both cases is a null read - the end of the script, EOF. It's not a newline, but that is a pedantic argument to make on my part anyway. Still, the answers linked don't come anywhere close to discussing that. By spec: *The application shall not present a script that violates the restrictions of a text file except that the final character need not be a newline.* – mikeserv Jun 03 '15 at 07:07

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