Python, Python. . , , - .
import fileinput
import os
os.chdir( os.path.join("c:\\","path") )
for file in os.listdir("."):
for line in fileinput.input(file,inplace=0):
if "search word" in line :
line=line.replace("search word","new word")
print line
( inplace=1 ). script Python script .