Common Python os Module Functions for Automation and File Management

Below is a collection of frequently used Python methods for automation and file system operations.

os.getcwd() – obtain the current working directory.

os.listdir() – return all files and directory names under a specified path.

os.remove() – delete a single file.

os.removedirs(r"c:\python") – delete multiple directories (use with caution).

os.path.isfile() – check whether a given path is a file.

os.path.isdir() – check whether a given path is a directory.

os.path.isabs() – determine if a path is absolute.

os.path.exists() – verify that a path actually exists.

os.path.split() – split a path into directory and file name components.

Example: import os then os.path.split('/home/swaroop/byte/code/poem.txt') returns ('/home/swaroop/byte/code', 'poem.txt') .

os.path.splitext() – separate the file extension.

os.path.dirname() – get the directory name of a path.

os.path.basename() – get the file name of a path.

os.system() – execute a shell command.

os.getenv() and os.putenv() – read and set environment variables.

os.linesep – platform-specific line separator (e.g., '\r\n' on Windows, '\n' on Linux).

os.name – identify the operating system ('nt' for Windows, 'posix' for Unix/Linux).

os.rename(old, new) – rename a file or directory.

os.makedirs(r"c:\python\test") – create nested directories.

os.mkdir("test") – create a single directory.

os.stat(file) – retrieve file attributes.

os.chmod(file) – modify file permissions or timestamps.

os._exit() – terminate the current process (available in Python 2.4+).

os.path.getsize(filename) – obtain file size.

File operations:

os.mknod("test.txt") – create an empty file.

fp = open("test.txt", "w") – open a file for writing (creates it if it does not exist).

Common file open modes:

w – write (truncate existing file).

a – append (create if needed).

r+ – read/write.

w+ – read/write (truncates).

a+ – read/write with append.

rb , wb , ab – binary read, write, append.

rb+ , wb+ , ab+ – binary read/write/append.

File object methods:

fp.read([size]) – read up to *size* bytes.

fp.readline([size]) – read a single line.

fp.write(str) – write a string (no newline added automatically).

fp.writelines(seq) – write an iterable of strings.

fp.close() – close the file.

fp.flush() – flush internal buffer to disk.

fp.fileno() – return the file descriptor.

fp.isatty() – check if the file is a terminal device.

fp.tell() – get current file pointer position.

fp.seek(offset[, whence]) – move file pointer; *whence* = 0 (start), 1 (current), 2 (end).

fp.truncate([size]) – truncate file to *size* bytes (default current position).

Directory operations (often via os or shutil ):

os.mkdir("file") – create a directory.

shutil.copyfile("oldfile", "newfile") – copy a file.

shutil.copy("oldfile", "newfile") – copy a file; destination may be a directory.

shutil.copytree("olddir", "newdir") – copy an entire directory tree (target must not exist).

os.rename("oldname", "newname") – rename a file or directory.

shutil.move("oldpos", "newpos") – move a file or directory.

os.remove("file") – delete a file.

os.rmdir("dir") – remove an empty directory.

shutil.rmtree("dir") – recursively delete a directory and its contents.

os.chdir("path") – change the current working directory.

Additional notes on file pointer manipulation:

seek(offset, where) – move pointer; *where* = 0 (start), 1 (current), 2 (end).

tell() – returns current pointer position, unaffected by truncate() .

truncate(n) – cut file to *n* characters from the start (or from current position if *n* omitted).

readline(n) – read a line up to *n* bytes; default reads the whole line.

readlines() – read all lines into a list.

read() – read the entire file.

Example demonstrating file operations:

<code>fso = open("f:\\a.txt", 'w+')
print fso.tell()          # 0
fso.write("abcde\n")
print fso.tell()          # 7
fso.write("fghwm")
print fso.tell()          # 12
fso.seek(1, 0)
print fso.tell()          # 1
print fso.readline()     # reads from position 1, outputs 'bcde'
print fso.tell()          # 7
fso.truncate(8)
print fso.tell()          # still 7, file now contains 'abcde\nf'
print fso.readline()      # reads from position 8, outputs 'f'
</code>

The article concludes with a QR code for a free Python public course and additional recommended reading links.