Question

I would like to capture special character from a line:

var=`echo "#this is comment" | grep "[^a-zA-Z0-9 \t]"`
echo $var

Expected Output: #

But getting: #this is comment

Can someone help me out.

Answer 1

It seems like you want something more like:

var=`echo "#this is comment" | sed 's/[^a-zA-Z0-9 \t]//g;'`

Using sed will replace the characters; using grep was only searching for the characters.

Edit: Note that the \t construct is not guaranteed to be portable to all systems or locales; I believe if your sed supports POSIX regular expressions, using [:space:] may work better. (thanks @ghoti!)