Output file was not created error when merging TIFF files using GDAL

Question

Merge TIFF files using GDAL. Output file was not created. How can I solve it?

Code

import subprocess
import glob
import os
import shlex

file_list = glob.glob(r"E:\Spekter\data\data\Task2\*.tif")
files_string = " ".join(file_list)
output_path = r"E:\Spekter\Task 2\output.tif"
command = f"gdal_merge.py -o {output_path} -of gtiff {files_string}"

print("Command:", command)
os.system(command)

if os.path.exists(output_path):
  print(f"Output file '{output_path}' created successfully.")
else:
  print("Output file was not created. Check for errors and permissions.")

Output

Command: gdal_merge.py -o E:\Spekter\Task 2\output.tif -of gtiff E:\Spekter\data\data\Task2\618_5405.tif E:\Spekter\data\data\Task2\618_5406.tif E:\Spekter\data\data\Task2\618_5407.tif E:\Spekter\data\data\Task2\619_5403.tif E:\Spekter\data\data\Task2\619_5404.tif E:\Spekter\data\data\Task2\619_5405.tif E:\Spekter\data\data\Task2\619_5406.tif E:\Spekter\data\data\Task2\619_5407.tif E:\Spekter\data\data\Task2\619_5408.tif E:\Spekter\data\data\Task2\619_5409.tif E:\Spekter\data\data\Task2\620_5400.tif E:\Spekter\data\data\Task2\620_5401.tif E:\Spekter\data\data\Task2\620_5402.tif E:\Spekter\data\data\Task2\620_5403.tif E:\Spekter\data\data\Task2\620_5404.tif E:\Spekter\data\data\Task2\620_5405.tif E:\Spekter\data\data\Task2\620_5406.tif E:\Spekter\data\data\Task2\620_5407.tif E:\Spekter\data\data\Task2\620_5408.tif E:\Spekter\data\data\Task2\620_5409.tif
Output file was not created. Check for errors and permissions.

Answer 1

I modified your code slightly

import subprocess
import glob
import os
import shlex

file_list = glob.glob(r"C:\data\dem\P*.tif")
files_string = " ".join(file_list)
output_path = r"C:\data\dem\output.tif"
command = f"gdal_merge.py -o {output_path} -of gtiff {files_string}"

print("Command:", command)
os.system(command)

if os.path.exists(output_path):
  print(f"Output file '{output_path}' created successfully.")
else:
  print("Output file was not created. Check for errors and permissions.")

Then I executed it successfully:

python mergetest.py
Command: gdal_merge.py -o C:\data\dem\output.tif -of gtiff C:\data\dem\Ptest.tif
0...10...20...30...40...50...60...70...80...90...100 - done.
Output file 'C:\data\dem\output.tif' created successfully.

It worked also with a longer {files_string}. Your code works, check again the input and output strings.