[R] Replacing Period in String

[Sparks, John James]

Dear R Users,

I am working with gsub for the first time.  I am trying to remove some
characters from a string.  I have hit the problem where the period is the
shorthand for 'everything' in the R language when what I want to remove is
the actual periods.  In the example below, I simply want to remove the
periods as I have removed the comma, but instead the complete string is
wiped out.  I would appreciate it if someone could let me know how I
communicate that I want to remove the period verbatim to R.

Many thanks.
--John Sparks

> txt="This is a test. However, it is only a test."
> txt2<-gsub(",","",txt)
> txt2
[1] "This is a test. However it is only a test."
> txt3<-gsub(".","",txt)
> txt3
[1] ""
>