Expanding on don_crissti's comment, the * operator in a regular expression needs an operand; in your case, . which stands for "any character":

grep -E -rnw ".*BCR.*" ~/Dropbox 

You can get the same result without using a regular expression:

grep -rn BCR ~/Dropbox 

Expanding on don_crissti's comment, the * operator in a regular expression needs an operand; in your case, . which stands for "any character":

grep -E -rnw ".*BCR.*" ~/Dropbox 

You can get the same result without using a regular expression:

grep -rn BCR ~/Dropbox 

Expanding on don_crissti's comment, the * operator in a regular expression needs an operand; in your case, . which stands for "any character":

grep -E -rnw ".*BCW.*" ~/Dropbox 

You can get the same result without using a regular expression:

grep -rn BCW ~/Dropbox 

Expanding on don_crissti's comment, the * operator in a regular expression needs an operand; in your case, . which stands for "any character":

grep -E -rnw ".*BCR.*" ~/Dropbox 

You can get the same result without using a regular expression:

grep -rn BCR ~/Dropbox