Read expression for grep from standard input
How can I make grep read the expression from standard input (stdin)?
For example (the following doesn't work):
grep -i -f &0 /path/to/text/file < "/regexp/"
Solution 1:
Use -f with a single dash to denote the standard input:
$ echo Content | grep -f - notice.html
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
...
Note: This has been tested with GNU grep - I am not sure if it's specified by POSIX.