songbird (2018-08-27): > me@ant(25)$ env | grep -F "-g" > grep: invalid option -- 'g'
Maybe what you want is an explanation rather than just a solution.
Quotes are for the shell: they protect arguments that contain special
characters, so that commands get them as is.
For example, you need to write:
echo "Fire*Wolf"
because without the quotes, the shell would try to find all the files in
the current directory with a name that matches the pattern.
Since the dash is not special for the shell, the quotes are unnecessary.
They do no harm, but have no consequences here:
grep "-g"
grep '-g'
grep -g
grep ""''""-"g"''
all invoke grep with one extra argument "-g".
The dash is special for programs that understand options (some do not;
some do with a different syntax, for example key=value), and need to be
escaped the way programs expect it. The usual escaping is that an
argument "--" means all following arguments are not options, even if
they start with a dash.
> me@ant(26)$ env | grep -F '-g'
> grep: invalid option -- 'g'
Same as above.
> me@ant(28)$ env | grep '\-g'
> CFLAGS=-g
grep sees the argument starting with a backslash, it is not an option,
therefore it is the regexp. But backshash-dash could have had a special
semantic, like backslash-parentheses.
> me@ant(29)$ env | grep '-g'
> grep: invalid option -- 'g'
Same as above.
> me@ant(30)$ env | grep "-g"
> grep: invalid option -- 'g'
Same as above.
Regards,
--
Nicolas George
signature.asc
Description: Digital signature
