Hello. The task is to write a regular expression to search for email in the file. It turned out like this:

^[a-zA-Z][A-Za-z0-9._-]+@[A-Za-z0-9]+\.[A-Za-z]{2,6}\b

on this resource >> https://regex101.com/ << shows what seems to work, but the result in the terminal is not at all working. What could be a mistake?

Another ideal would be to add an expression to exclude results with the sequence ".-", for this I wrote this:

 ^[a-zA-Z](?\!.-)[A-Za-z0-9._-]+@[A-Za-z0-9]+\.[A-Za-z]{2,6}\b

but no answer ...

  • Did you forget the screening in the terminal? - andreymal
  • @andreymal ... (?! .-) ... here, before the exclamation backslash? Put in question simply forgot to add - Alex
  • For this, even a special website is emailregex.com - Mike
  • 2
    I would suggest reducing all your question to such a "Regular expression works on regex101, but does not work in grep" - all the rest is superfluous information that confuses the respondents. They think that the problem is that email is somehow not as verified as in one of the answers below. - ReinRaus
  • Give a grep command that does not work for you. - ReinRaus

2 answers 2

It is very difficult to check e-mail through regular expressions in full compliance with RFC822 :

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It is possible that this regular expression is outdated after the resolution of the first-level multi-letter domains (I canโ€™t verify it myself - the above expression is difficult to analyze).

So the only way to check the email is guaranteed - send a letter to him.

  • @Visman, you need to remove the newline characters: regex101.com/r/tL0fM3/1 - ฿Š฿š฿ค฿˜
  • I checked with the modifier x . - Visman September

Regular expression with positional checking (for egrep):

 ^(?![^@]*\.-)[a-zA-Z][A-Za-z0-9._-]+@[A-Za-z0-9]+\.[A-Za-z]{2,6}\b

Everything is simple: we exclude the sequence with one positional check .-

https://regex101.com/r/kL9pW1/1

Regular expression without positional checking (for grep):

 ^[a-zA-Z](?:\.+[A-Za-z0-9_]|[A-Za-z0-9_-])+\.?@[A-Za-z0-9]+\.[A-Za-z]{2,6}\b

  1. One or more dots with no dashes behind:

     \.+[A-Za-z0-9_]

  2. Not a point:

     [A-Za-z0-9_-]
  3. Points 1 and 2 as many times as you like.

  4. Perhaps - one point in front of the dog:

     \.?

https://regex101.com/r/kL9pW1/2