matching a line with a literal asterisk “*” in grep

Question

Tried

$ echo \"$STRING\" | egrep \"(\\*)\"

and also

$ echo \"$STRING\" | egrep \'(\\*)\'

and countless ot

Answer 1

Simply escape the asterisk with a backslash:

grep "\*"

Answer 2

echo "$STRING" | fgrep '*'

fgrep is used to match the special characters.

Answer 3

Try a character class instead

echo "$STRING" | egrep '[*]' 

Answer 4

Use:

grep "*" file.txt

or

cat file.txt | grep "*"

Answer 5

Here's one way to match a literal asterisk:

$ echo "*" | grep "[*]"
*
$ echo "*" | egrep "[*]"
*
$ echo "asfd" | egrep "[*]"
$ echo "asfd" | grep "[*]"
$ 

Wrapping an expression in brackets usually allows you to capture a single special character easily; this will also work for a right bracket or a hyphen, for instance.

Be careful when this isn't in a bracket grouping:

$ echo "hi" | egrep "*"
hi
$ echo "hi" | grep "*"
$