I want to search the phone-number in a text file using grep in cygwin.
The number is 0570-2770521, and I use the regular expression
"[0-9]{4}-[0-9]{7}" with total command as grep "[0-9]{4}-[0-9]{7}" ./list.txt, but it didn't work.
Then I changed to grep "[0-9]\{4\}-[0-9]\{7\}" ./list.txt, it works!
But since the {} are metacharacters, if escape them, they will be just literal characters, then how can they represent the match times of [0-9]?
Does that I got a wrong understanding? Hope someone can help to explain the confusion, thanks in advance!
Best regards!
man re_format:
Obsolete ("basic") regular expressions differ in several respects. [...] The delimiters for bounds are
\{and\}, with{and}by themselves ordinary characters.
Use egrep (or, equivalently, grep -E) for enhanced regular expressions, which may be more familiar to you.