lispdoc - results for probe-file

(probe-file pathspec)

Function: Return the truename of PATHSPEC if the truename can be found, or NIL otherwise. See TRUENAME for more information.

Example:

(defun file-exists-p (pathname)
  "Similar to CL:PROBE-FILE except it always returns directory names
in `directory normal form'. Returns truename which will be in
`directory form' if file named is, in fact, a directory."
  (probe-file pathname))

Mentioned in:
CLtL2 - 23.1.5.3. Using Logical Pathnames
CLtL2 - 23.3. Renaming, Deleting, and Other File Operations
HyperSpec - Function PROBE-FILE
PCL - interacting with the file system
PCL - testing a files existence
PCL - the api
PCL - walking a directory tree