os

methods

✅ os (Standard Library for OS Operations)

pythonCopyEditimport os

Function/Property	Description
os.getenv()	Get environment variable
os.environ	Dict of environment variables
os.path.exists()	Check if file/path exists
os.path.join()	Join file paths
os.listdir()	List files in directory
os.remove()	Delete file
os.rename()	Rename file or directory
os.mkdir() / os.makedirs()	Create directory (single/all levels)
os.rmdir() / os.removedirs()	Remove directory
os.system()	Run shell command
os.path.basename()	Get filename from path
os.path.abspath()	Get absolute path
os.chmod()	Change permission of file
os.getcwd()	Get current working directory
os.chdir()	Change current working directory
os.walk()	Recursively traverse directory structure
os.stat()	Get file metadata

example

Here’s a DevOps/SRE-centric guide for Python's os module, with real-world examples for each function/property — ideal for scripts managing environments, files, directories, and shell tasks.

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✅ os — Python Standard Library for OS Operations

First, import the module:

import os

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🔹 os.getenv() — Access AWS Credentials from Env

aws_key = os.getenv("AWS_ACCESS_KEY_ID")
print("AWS Key:", aws_key)

📌 Use in automation scripts to securely read secrets/vars.

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🔹 os.environ — Set Temporary Env Var

os.environ["ENV"] = "production"
print("ENV:", os.environ["ENV"])

📌 Useful for CI/CD jobs or subprocesses.

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🔹 os.path.exists() — Check If Config File Exists

if os.path.exists("/etc/nginx/nginx.conf"):
    print("Nginx config found")

📌 Use before applying configs or restarts.

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🔹 os.path.join() — Build File Paths Safely

path = os.path.join("/var/log", "app", "error.log")
print(path)

✅ Avoids OS-specific path bugs.

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🔹 os.listdir() — List Backup Files

files = os.listdir("/backups")
print("Backup files:", files)

📌 Handy for cleanup, audits, and automation.

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🔹 os.remove() — Delete Old Log File

os.remove("/tmp/old.log")
print("Old log deleted")

⚠️ Be cautious; it deletes immediately.

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🔹 os.rename() — Rotate Log File

os.rename("app.log", "app.log.1")
print("Log rotated")

📌 Used in log rotation or temp file handling.

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🔹 os.mkdir() / os.makedirs() — Create Directories

os.makedirs("/tmp/devops/logs", exist_ok=True)
print("Directories created")

✅ makedirs() creates all intermediate folders.

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🔹 os.rmdir() / os.removedirs() — Remove Directories

os.rmdir("/tmp/test")
os.removedirs("/tmp/devops/logs")

📌 Use in teardown or cleanup scripts.

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🔹 os.system() — Execute Shell Command

os.system("systemctl restart nginx")

⚠️ Avoid in untrusted input cases — use subprocess instead for security.

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🔹 os.path.basename() — Get Filename from Path

print(os.path.basename("/var/log/nginx/error.log"))
# Output: error.log

📌 Used in logs and reports.

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🔹 os.path.abspath() — Get Absolute Path

print(os.path.abspath("deploy.sh"))

✅ Use for clarity and robustness in scripts.

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🔹 os.chmod() — Set File Permissions

os.chmod("script.sh", 0o755)

📌 Automate deploy scripts with correct permissions.

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🔹 os.getcwd() — Get Current Directory

print("Current working directory:", os.getcwd())

📌 Useful in debugging or directory-aware scripts.

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🔹 os.chdir() — Switch Working Directory

os.chdir("/var/www")
print("Switched to:", os.getcwd())

📌 Use in deploy scripts to ensure correct context.

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🔹 os.walk() — Recursive Directory Traversal

for dirpath, dirs, files in os.walk("/var/log"):
    for file in files:
        print(os.path.join(dirpath, file))

📌 Use for backups, audits, or large cleanups.

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🔹 os.stat() — Get File Metadata

info = os.stat("app.log")
print(f"Size: {info.st_size} bytes | Modified: {info.st_mtime}")

📌 Use for log monitoring, age-based cleanup.

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✅ Summary Table

Function / Property	DevOps/SRE Use Case
os.getenv()	Read secrets or config from env vars
os.environ	Set variables for scripts or subprocesses
os.path.exists()	Check config/log presence
os.path.join()	Build platform-safe paths
os.listdir()	List log or backup files
os.remove()	Delete old files/logs
os.rename()	Rotate or move files
os.mkdir() / makedirs()	Create deploy or backup folders
os.rmdir() / removedirs()	Teardown or cleanup directories
os.system()	Run shell commands (e.g., service restart)
os.path.basename()	Extract filenames for reports
os.path.abspath()	Normalize paths
os.chmod()	Set script permissions
os.getcwd()	Get script context
os.chdir()	Change to deploy or log directory
os.walk()	Traverse entire directory tree
os.stat()	Fetch size, timestamps, etc.

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