renamer.py

# nuke channal ranamer

import os
import nuke

def renamer(old_line, new_line):
    input_file = nuke.root().knob('name').value() # read nuke script path 
    if not os.path.isfile(input_file): # checking file availability
        print 'no file', input_file
        return
    with open(input_file, 'r') as f: # Open file for reading
        data = f.readlines() #Read data from file to list
    filename, file_extension = os.path.splitext(input_file) # Separate file name and its extension
    output_file = filename + '_new' + file_extension # create a new file name
    print 'input file: ', input_file
    print 'output file: ', output_file
    f_write = open(output_file, 'w') # Open file for writing
    for line in data:
        if old_line in line: # If we find the old line in string
            f_write.write(line.replace(old_line, new_line)) #change old to new and write
            continue
        f_write.write(line) # writing unchanged
    f_write.close()
    print '\nrename done'


old_line = nuke.getInput('Old line', 'ld01')
new_line = nuke.getInput('New line', 'ld02')
if new_line and old_line:
    renamer(old_line, new_line)

else:
    print 'Enter values in the fields'