@ch,
You can add $. , / using regular list syntax. But you cannot add \ to a list using regular syntax.
> list("$",".",",","/","~")
[[1]]
[1] "$"
[[2]]
[1] "."
[[3]]
[1] ","
[[4]]
[1] "/"
[[5]]
[1] "~"
you can add \\ but not \.
> list("\\")
[[1]]
[1] "\\"
> list("\")
+ ""
+ ""
Error: unexpected string constant in:
"""
""