Regular expression to limit number of characters to 10

You can use curly braces to control the number of occurrences. For example, this means 0 to 10:

/^[a-z]{0,10}$/

The options are:

• {3} Exactly 3 occurrences;
• {6,} At least 6 occurrences;
• {2,5} 2 to 5 occurrences.

See the regular expression reference.

Your expression had a + after the closing curly brace, hence the error.

/^[a-z]{0,10}$/ should work. /^[a-z]{1,10}$/ if you want to match at least one character, like /^[a-z]+$/ does.

It might be beneficial to add greedy matching to the end of the string, so you can accept strings > than 10 and the regex will only return up to the first 10 chars. /^[a-z0-9]{0,10}$?/

grep '^[0-9]\{1,16\}' | wc -l

Gives the counts with exact match count with limit