dot-check_valid_util: Checks for valid members of subdirectory
In snystrom/dotargs: Framework for Building Interfaces to Shell Commands

Description Usage Arguments Value Examples

Not meant to be called directly

1	.check_valid_util(util, utils = NULL, path = NULL)

`util`	name of target located in path
`utils`	name of supported targets in path
`path`	path to directory

safe path to util, or error if util does not exist

if (.Platform$OS.type == "unix") {
# this will return /full/path/to/bin
# or return an error for all values of util that are not "ls" and "pwd"
# or error if "ls" does not exist in "/bin"
.check_valid_util("ls", utils = c("ls", "pwd"), "/bin")

## Not run: 
# This will throw error
.check_valid_util("badUtil", utils = c("ls", "pwd"), "/bin")

## End(Not run)
}