\{\} in regular expression--number of occurrences of the matching pattern

Regular Expressions:

\{\} matches the number of occurrences of a character

Use * to match all matching results once, but if you set the number of times, you should use \{\}, this mode has three forms.

Pattern\{n\} match pattern appears n times

Pattern\{n,\} match pattern appears at least n times

Pattern\{n,m\} match pattern appears n to M times, N,m is any integer between 0-255

Cases:

A\{2\}b Match value is AaB

A\{4\}b Match value is Aaaab or Aaaaaab, but cannot be Aaab

A\{3,5\} match value is Aaab,aaaab,aaaaab

Note: Regular expression single metacharacters are not difficult to use, especially if multiple meta-character sets appear mixed

grep ' ^h.[a-z,a-z]s\{2,4\}c$'./test

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\{\} in regular expression--number of occurrences of the matching pattern