Regular Expression usage with ls

Question

I am trying to use ER (Extended Regular Expressions) with ls like ls .+\\..+.

I am trying to print all files which contains an ext

Answer 1

You are confusing regular expression with shell globbing. If you want to use regular expression to match file names you could do:

$ ls | egrep '.+\..+'

Answer 2

You don't say what shell you are using, but they generally don't support regular expressions that way, although there are common *nix CLI tools (grep, sed, etc) that do.

What shells like bash do support is globbing, which uses some similiar characters (eg, *) but is not the same thing.

Newer versions of bash do have a regular expression operator, =~:

for x in `ls`; do 
    if [[ $x =~ .+\..* ]]; then 
        echo $x; 
    fi; 
done