import glob, os
os.chdir("/mydir")
for file in glob.glob("*.txt"):
    print(file)

import os
for file in os.listdir("/mydir"):
    if file.endswith(".txt"):
        print(os.path.join("/mydir", file))

import os
for root, dirs, files in os.walk("/mydir"):
    for file in files:
        if file.endswith(".txt"):
             print(os.path.join(root, file))

>>> import glob
>>> glob.glob('./*.txt')
['./outline.txt', './pip-log.txt', './test.txt', './testingvim.txt']

for root, dirs, files in os.walk(directory):
    for file in files:
        if file.endswith('.txt'):
            print file

>>> import os
>>> path = '/usr/share/cups/charmaps'
>>> text_files = [f for f in os.listdir(path) if f.endswith('.txt')]
>>> text_files
['euc-cn.txt', 'euc-jp.txt', 'euc-kr.txt', 'euc-tw.txt', ... 'windows-950.txt']

import os

path = 'mypath/path' 
files = os.listdir(path)

files_txt = [i for i in files if i.endswith('.txt')]

import os, os.path

for root, dirs, files in os.walk(dir):
    for f in files:
        fullpath = os.path.join(root, f)
        if os.path.splitext(fullpath)[1] == '.txt':
            print fullpath

import os, os.path

fileiter = (os.path.join(root, f)
    for root, _, files in os.walk(dir)
    for f in files)
txtfileiter = (f for f in fileiter if os.path.splitext(f)[1] == '.txt')
for txt in txtfileiter:
    print txt

import pathlib

list(pathlib.Path('your_directory').glob('*.txt'))

for txt_file in pathlib.Path('your_directory').glob('*.txt'):
    # do something with "txt_file"

import glob
for f in glob.iglob("/mydir/*/*.txt"): # generator, search immediate subdirectories 
    print f

print glob.glob1("/mydir", "*.tx?")  # literal_directory, basename_pattern

import fnmatch, os
print fnmatch.filter(os.listdir("/mydir"), "*.tx?") # include dot-files

from path import path
p = path('/path/to/the/directory')
for f in p.files(pattern='*.txt'):
    print f

import os

the_dir = 'the_dir_that_want_to_search_in'
all_txt_files = filter(lambda x: x.endswith('.txt'), os.listdir(the_dir))

import os

def findFilesInFolder(path, pathList, extension, subFolders = True):
    """  Recursive function to find all files of an extension type in a folder (and optionally in all subfolders too)

    path:        Base directory to find files
    pathList:    A list that stores all paths
    extension:   File extension to find
    subFolders:  Bool.  If True, find files in all subfolders under path. If False, only searches files in the specified folder
    """

    try:   # Trapping a OSError:  File permissions problem I believe
        for entry in os.scandir(path):
            if entry.is_file() and entry.path.endswith(extension):
                pathList.append(entry.path)
            elif entry.is_dir() and subFolders:   # if its a directory, then repeat process as a nested function
                pathList = findFilesInFolder(entry.path, pathList, extension, subFolders)
    except OSError:
        print('Cannot access ' + path +'. Probably a permissions error')

    return pathList

dir_name = r'J:\myDirectory'
extension = ".txt"

pathList = []
pathList = findFilesInFolder(dir_name, pathList, extension, True)

from os import listdir
from os.path import isfile, join
path = "/dataPath/"
onlyTxtFiles = [f for f in listdir(path) if isfile(join(path, f)) and  f.endswith(".txt")]
print onlyTxtFiles

import os
import sys 

if len(sys.argv)==2:
    print('no params')
    sys.exit(1)

dir = sys.argv[1]
mask= sys.argv[2]

files = os.listdir(dir); 

res = filter(lambda x: x.endswith(mask), files); 

print res

import os
import pathlib
import timeit
import glob

def a():
    path = pathlib.Path().cwd()
    list_sqlite_files = [str(f) for f in path.glob("*.sqlite")]

def b(): 
    path = os.getcwd()
    list_sqlite_files = [f.path for f in os.scandir(path) if os.path.splitext(f)[1] == ".sqlite"]

def c():
    path = os.getcwd()
    list_sqlite_files = [os.path.join(path, f) for f in os.listdir(path) if f.endswith(".sqlite")]

def d():
    path = os.getcwd()
    os.chdir(path)
    list_sqlite_files = [os.path.join(path, f) for f in glob.glob("*.sqlite")]

def e():
    path = os.getcwd()
    list_sqlite_files = [os.path.join(path, f) for f in glob.glob1(str(path), "*.sqlite")]

def f():
    path = os.getcwd()
    list_sqlite_files = []
    for root, dirs, files in os.walk(path):
        for file in files:
            if file.endswith(".sqlite"):
                list_sqlite_files.append( os.path.join(root, file) )
        break

print(timeit.timeit(a, number=1000))
print(timeit.timeit(b, number=1000))
print(timeit.timeit(c, number=1000))
print(timeit.timeit(d, number=1000))
print(timeit.timeit(e, number=1000))
print(timeit.timeit(f, number=1000))

# Python 3.6.4
0.431
0.515
0.161
0.548
0.537
0.274

import glob, os
os.chdir("H:\\wallpaper")# use whatever you directory 

#double\\ no single \

for file in glob.glob("**/*.psd", recursive = True):#your format
    print(file)

import fnmatch
import os

for file in os.listdir('.'):
    if fnmatch.fnmatch(file, '*.txt'):
        print file

import os
fnames = ([file for root, dirs, files in os.walk(dir)
    for file in files
    if file.endswith('.txt') #or file.endswith('.png') or file.endswith('.pdf')
    ])
for fname in fnames: print(fname)

import os
fileNames = [fileName for fileName in os.listdir("data") if fileName.endswith(".txt")]

import fnmatch
import os

    for file in os.listdir("/Users/Johnny/Desktop/MyTXTfolder"):
        if fnmatch.fnmatch(file.upper(), '*.TXT'):
            print(file)

from fnmatch import filter
from functools import partial
from itertools import chain
from os import path, walk

print(*chain(*(map(partial(path.join, root), filter(filenames, "*.txt")) for root, _, filenames in walk("mydir"))))