Using the Linux terminal.

Given the file name is os_osx2.h which is encoded, how do you decode os_osx2.h using the 'tr' command?

Use 'tr' to rotate the letters back into place and get the name of the next file.

Once you have found the 2nd file, you have to decode it. This next file has had the characters rotated in a substitution cypher. The set of letters a-zA-Z has been rotated by between 1 and 5 characters backwards (e.g., if rotating by 1 character, a becomes Z, b becomes a, c became b, etc.). You must rotate the characters in the file in the opposite direction the correct number of places (in the range of 1-5 places) to read the contents.