numeric - How to take out the numerical values from a list of numbers and words in linux

Question

I'm a newbie in Linux. I was trying to make a nested if loop inside a for loop and found difficulties taking out the numeric values from a list. My code is

 #!/bin/bash
t=`ls ListOfthings`
for i in $t
do
  if "$i" -eq "$i"
 then
    echo hi (for example)
fi
done

when I execute this, it said syntax error unexpected token 'done'. I think its some problems related to the "$i" -eq "$i"? Is this the right way to identify the numerical items?

For example, from a list [123 23 63 a.txt b.txt c.sh], 123, 23 and 63 are needed.

question from:https://stackoverflow.com/questions/66057953/how-to-take-out-the-numerical-values-from-a-list-of-numbers-and-words-in-linux

Answer 1

Try using regex. For example: egrep '^[0-9]+$' list

Or if you're using ls: ls | egrep '^[0-9]+$'