failed to read raw data from a physical folder.

[Meilu]

ERROR: Physical file does not exist, /home/???/SASIntro/Data/ch2/trans.txt.

but the file does exist.

[Tom]

Double check the filename.  Remember that on a Unix system the case of the letters in a file's name is significant.  So Data is a different directory than data.

Also make sure you are looking for the file on the system where SAS is running.  Not the system where you are running Enterprise Guide or the browser you used to connect to SAS/Studio.