gistfile1.py

import os, arcpy

#create blank text file
with open("C:\\Temp\\GISlayers.txt", "w") as txt:
    for root, dirs, files in os.walk("C:\\Temp\\temp"):
        for f in files:
            #look for shapefiles
            if f.endswith('.shp') or f.endswith('.lyr') or
               f.endswith('.img'):
                desc = arcpy.Describe(root + "\\" + f)
                #write info to text file
                txt.write(desc.name + "," + desc.catalogPath + "\n")

            #look for file geodatabases
            if f.endswith('.gdb'):
                desc = arcpy.Describe(root)
                for child in desc.children:
                    #write info to text file
                    txt.write(child.name + "," + child.path + "\n")