I'm trying to use something like the pattern "John.*Smith" but instead of matching anything in between John and Smith I'd like to match anything between the words as long as it's of X characters length or less.
If X = 5 for instance:
Lines that should be a match:
- John Smith
- Jonh F. Smith
Lines that shouldn't be a match:
- John Ferdinand Smith
- Joe Brown; John Johson; Mary Smith
How could I do that with grep?
Try using a "bound".
man regex:
A bound is '{' followed by an unsigned decimal integer, possibly followed by ',' possibly followed by another unsigned decimal integer, always followed by '}'. The integers must lie between 0 and RE_DUP_MAX (255(!)) inclusive, ...
grep -E "John.{0,5}Smith" file
John Smith
John F. Smith
The 0 can be omitted (EDIT: in some implementations):
grep -E "John.{,5}Smith" file
Johnnie Smith. Or Mark John; Smith L.J.. Something like John [^;]{0,3} Smith might work to avoid that.
I would use the following command :
grep 'John.\{,5\}Smith'
. is for any characters.
\{,5\} is for the repetition up to 5 times.
grep -E or egrep.
Commented
Nov 10, 2021 at 21:07
,n is for up to 5, which is was in the question.
Commented
Nov 10, 2021 at 21:23
grep, it's \{n,m\} with backslashes. In "extended regexes" or ERE, as used by grep -E (and awk and closer to what the more modern ones like Perl regexes look like), it's {n,m} without backslashes.
{,5} and not {0,5}) seems to work in GNU grep and GNU awk, but not in whatever the grep on my Mac is (gives an error), nor in Perl (warns, and matches the characters literally). So yeah, just spell out the 0.