You can make the pattern more specific matching lowercase chars with a hyphen and matching 1 or more digits at the end

• ^ Start of string
• [a-z]\+ Match 1+ chars a-z
• - Match literally
• [a-z]\+ Match 1+ chars a-z
• [0-9]\+ Match 1+ digits
• $ End of string

For example

echo "abc-def1-xxx
abc-def2-yy-vv
abc-def3
abc-def4" | grep '^[a-z]\+-[a-z]\+[0-9]\+$'

Output

abc-def3
abc-def4

You could also match for example abc-def and then 1 or more digits:

^abc-def[0-9]\+$

Let's say the data in put in a file, data.txt

abc-def1-xxx
abc-def2-yy-vv
abc-def3
abc-def4

The command to get the last two lines is:

grep -E '*[0-9]$' data.txt

Explanation:

• -E, the pattern is interpreted as an extended regular expression.
• *: any character
• [0-9]: one digit
• $: ends with the character just before the $. So here, it indicates that the string must end with a digit.

So it looks at the lines in data.txt, and outputs the lines where the last character is a digit, from 0 to 9.