| glob2rx {utils} | R Documentation | 
Change wildcard aka globbing (or “ls” like)
pattern into the corresponding regular expression (regexp).
glob2rx(pattern, trim.head = FALSE, trim.tail = TRUE)
pattern | 
character vector | 
trim.head | 
logical specifying if leading "^.*" should be
trimmed from the result. | 
trim.tail | 
logical specifying if trailing ".*$" should be
trimmed from the result. | 
a character vector of the same length as the input pattern
where the “wild card” is translated to the corresponding
regular expression.
Martin Maechler, Unix/sed based version, 1991; current: 2004
regexp about regular expression,
sub, etc about substitutions using regexps.
stopifnot(glob2rx("abc.*") == "^abc\\.",
          glob2rx("a?b.*") == "^a.b\\.",
          glob2rx("a?b.*", trim.tail=FALSE) == "^a.b\\..*$",
          glob2rx("*.doc") == "^.*\\.doc$",
          glob2rx("*.doc", trim.head=TRUE) == "\\.doc$",
          glob2rx("*.t*")  == "^.*\\.t",
          glob2rx("*.t??") == "^.*\\.t..$"
)