Case-insensitive search of a list in R

I would suggest the grep() function and some of its additional arguments that make it a pleasure to use.

grep("stringofinterest",names(dataframeofinterest),ignore.case=TRUE,value=TRUE)

without the argument value=TRUE you will only get a vector of index positions where the match occurred.

Assuming that there are no variable names which differ only in case, you can search your all-lowercase variable name in tolower(names(myDataFrame)):

match("b", tolower(c("A","B","C")))
[1] 2

This will produce only exact matches, but that is probably desirable in this case.