accessing files from subfolders

Hi,
? There must be an easy way to do this, but I'm not finding it..

I'd just like to know the syntax to move up and down folder levels, without necessarily entering a full file path. ?Also, how to construct file and folder paths using variables.

For example 1, if I wanted to print to the screen the contents of a file called myFile.txt using the bash shell, I'd use the following:

cat ../myFile.txt

Also, for example 2, if I want to cd into a folder that contains my files, from within a loop, where the counter serves as one of the folders in the path.

In bash:

for i in {1..5} A B C # A, B, and C are also folder names
do
cd ~/${i} # move into (change working directory to?) my folder of interest, which is 1,2,3,4,5,A,B,or C
cat myFile.txt # print corresponding file of interest to screen
cd - # move back to the previous folder
done


I wonder if there's an easy corresponding way to accomplish this in R.

Any ideas most welcome!

Jonathan