A little script to find/replace strings in selected nodes’, parameter expressions:
import hou
sel = hou.selectedNodes()
dialog = hou.ui.readMultiInput('Find/Replace In Expression', input_labels=['Find: ', 'Replace: ',], buttons=("Find/Replace", "Cancel"),
severity=hou.severityType.ImportantMessage, title='Find/Replace', close_choice=1)
find = dialog[1][0]
replace = dialog[1][1]
if dialog[0] == 0:
for n in sel:
for parms in n.parms():
try:
newString = str(parms.eval()).replace(find, replace)
parms.set(newString)
except:
print ( '' )
try:
newExpression = str(parms.expression()).replace(find, replace)
parms.setExpression(newExpression)
except:
print ( '' )

thanks for this, use it all the time. noobs will appreciate if you add the brackets on the print statement for python 3!
Cheers. It only took 6 months!