Use grep to match a pattern in a line only once

Question

I have this:

echo 12345 | grep -o '[[:digit:]]\{1,4\}'

Which gives this:

1234
5

I understand whats happening. How do I stop grep from trying to continue matching after 1 successful match?

How do I get only

1234

Answer 1

You need to do the grouping: \(...\) followed by the exact number of occurrence: \{<n>\} to do the job:

maci:~ san$ echo 12345 | grep -o '\([[:digit:]]\)\{4\}'
1234

Hope it helps. Cheers!!