You are not logged in. Your edit will be placed in a queue until it is peer reviewed.
We welcome edits that make the post easier to understand and more valuable for readers. Because community members review edits, please try to make the post substantially better than how you found it, for example, by fixing grammar or adding additional resources and hyperlinks.
How to Edit
- Correct minor typos or mistakes
- Clarify meaning without changing it
- Add related resources or links
- Always respect the author’s intent
- Don’t use edits to reply to the author
How to Format
-
create code fences with backticks ` or tildes ~
```
like so
``` -
add language identifier to highlight code
```python
def function(foo):
print(foo)
``` - put returns between paragraphs
- for linebreak add 2 spaces at end
- _italic_ or **bold**
- indent code by 4 spaces
- backtick escapes
`like _so_` - quote by placing > at start of line
- to make links (use https whenever possible)
<https://example.com>[example](https://example.com)<a href="https://example.com">example</a>
How to Tag
A tag is a keyword or label that categorizes your question with other, similar questions. Choose one or more (up to 5) tags that will help answerers to find and interpret your question.
- complete the sentence: my question is about...
- use tags that describe things or concepts that are essential, not incidental to your question
- favor using existing popular tags
- read the descriptions that appear below the tag
If your question is primarily about a topic for which you can't find a tag:
- combine multiple words into single-words with hyphens (e.g. shell-script), up to a maximum of 35 characters
- creating new tags is a privilege; if you can't yet create a tag you need, then post this question without it, then ask the community to create it for you
-Foption since we're not using regex patterns, just plain string matching-F(surprisingly to me) appears to take a similar amount of time or even slightly slower (~5–10%). Hence, I'm not sure what the advantage would be.greppresumably has a special case for regexes with no metacharacters, because that's a common use-case. It's surprising thatfgrepwould be slower, but it's not surprising that the overhead of noticing this special case while compiling a short pattern is negligible vs. the time to scan a large file. (If it requires a special case at all to go that fast, vs. a pattern with a character class orx.*y.)greprecognizes any character other than\nnewline as a line separator. If not, the implicit^and$can still turn into a fixed-string search likestrstr(big_buf, "\n0\n"). (Or0\nat the start of a buffer.) But we're not just looking for the first match potentially far into a big buffer, we want to efficiently filter. But anyway, in theory yes it's just a 2-byte memcmp at the start of each line, and you'd hope that both fgrep and grep would see that.