Python: Environment variables

Python Basic: Exercise-53 with Solution

Access Environment Variables

Write a Python program to access environment variables.

Sample Solution-1:

Python Code:

# Import the 'os' module to access operating system-related functionality, including environment variables.
import os

# Print a separator for clarity.
print('*----------------------------------*')

# Print all environment variables.
print(os.environ)

# Print a separator for clarity.
print('*----------------------------------*')

# Access and print the 'HOME' environment variable.
print(os.environ['HOME'])

# Print a separator for clarity.
print('*----------------------------------*')

# Access and print the 'PATH' environment variable.
print(os.environ['PATH'])

# Print a separator for clarity.
print('*----------------------------------*')

Sample Output:

*----------------------------------*                                                                          
environ({'LESSOPEN': '| /usr/bin/lesspipe %s', '_': '/usr/bin/timeout', 'LIBVIRT_DEFAULT_URI': 'qemu:///system
', 'HOME': '/home/students', 'TERM': 'xterm-256color', 'SHELL': '/bin/bash', 'SHLVL': '2', 'USER': 'students',
 'MAIL': '/var/mail/students', 'COMP_WORDBREAKS': ' \t\n"\'><;|&(:', 'PATH': '/usr/local/bin:/usr/bin:/bin:/us
r/local/games:/usr/games', 'LANG': 'en_US.UTF-8', 'LOGNAME': 'students', 'LS_COLORS': 'rs=0:di=01;34:ln=01;36:
mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42
:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;3
1:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.d
z=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;
31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:
*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.jpg=01;35:*.jpeg=01;35:*.gif=01;35:*.
bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.p
ng=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.m
kv=01;35:*.webm=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wm
v=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01
;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36
:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:
*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:', 'JAVA_HOME': '/usr/lib/jvm/java-7-openjdk-amd
64/jre/bin/java', 'LESSCLOSE': '/usr/bin/lesspipe %s %s', 'PWD': '/home/students'})                           
*----------------------------------*                                                                          
/home/students                                                                                                
*----------------------------------*                                                                          
/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games                                                      
*----------------------------------*  

Explanation:

The ‘OS’ module provides a portable way of using operating system dependent functionality.

In the above exercise we imports the os module and uses it to print environment variables to the console output.

The environ attribute of the os module is a dictionary-like object that represents the environment variables in the current process. The print() function is used to print the entire dictionary of environment variables to the console using os.environ.

The code then uses square brackets ([]) to access specific environment variables by their names. In this case, it prints the values of the HOME and PATH environment variables to the console using os.environ['HOME'] and os.environ['PATH'], respectively.

Sample Solution-2:

Python Code:

# Import the 'os' module to access operating system-related functionality, including environment variables.
import os

# Iterate through all environment variables in the 'os.environ' dictionary.
for data in os.environ:
    # Print the name of the environment variable.
    print(data)
    # Print a separator for clarity.
    print('-' * 15)
    # Print the value of the environment variable.
    print(os.environ[data])
    # Print a line of '=' characters as an additional separator.
    print('=' * 30)

Sample Output:

exit_code
---------------
0
==============================
node_version
---------------
8.11.3
==============================
versioning
---------------
null
==============================
version
---------------
0.0.0
==============================
unstable_restarts
---------------
0
==============================
restart_time
---------------
47
==============================
pm_id
---------------
0
==============================
created_at
---------------
1621962710172
==============================
axm_dynamic
---------------
[object Object]
==============================
axm_options
---------------
[object Object]
==============================
axm_monitor
---------------
[object Object]
==============================
axm_actions
---------------

==============================
pm_uptime
---------------
1623108424625
==============================
status
---------------
launching
==============================
unique_id
---------------
f981135a-143b-43bf-8ca1-906432f1f9e1
==============================
PM2_HOME
---------------
/root/.pm2
==============================
PM2_INTERACTOR_PROCESSING
---------------
true
==============================
PM2_DISCRETE_MODE
---------------
true
==============================
PM2_PROGRAMMATIC
---------------
true
==============================
PYTHONPATH
---------------
/trinket/python3
==============================
MPLBACKEND
---------------
module://trinket_backend
==============================
TERM
---------------
xterm
==============================
HOME
---------------
/root
==============================
LC_ALL
---------------
en_US.UTF-8
==============================
LANGUAGE
---------------
en_US:en
==============================
LANG
---------------
en_US.UTF-8
==============================
DEBIAN_FRONTEND
---------------
teletype
==============================
HOSTNAME
---------------
4735090b6baa
==============================
PATH
---------------
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
==============================
NODE_APP_INSTANCE
---------------
0
==============================
vizion_running
---------------
false
==============================
km_link
---------------
false
==============================
pm_pid_path
---------------
/root/.pm2/pids/shell-0.pid
==============================
pm_err_log_path
---------------
/dev/null
==============================
pm_out_log_path
---------------
/dev/null
==============================
exec_mode
---------------
fork_mode
==============================
instances
---------------
1
==============================
exec_interpreter
---------------
node
==============================
pm_cwd
---------------
/trinket-workdir
==============================
pm_exec_path
---------------
/trinket-workdir/server/python3/shell.js
==============================
node_args
---------------

==============================
name
---------------
shell
==============================
env
---------------
[object Object]
==============================
merge_logs
---------------
true
==============================
vizion
---------------
true
==============================
autorestart
---------------
true
==============================
instance_var
---------------
NODE_APP_INSTANCE
==============================
pmx
---------------
true
==============================
automation
---------------
true
==============================
treekill
---------------
true
==============================
username
---------------
root
==============================
windowsHide
---------------
true
==============================
kill_retry_time
---------------
100
============================== 

Flowchart:

Sample Solution-3:

Python Code:

# Import the 'os' module to access operating system-related functionality, including environment variables.
import os

# Iterate through all environment variables and their values using the 'os.environ.items()' method.
for item, value in os.environ.items():
    # Print the environment variable name and its corresponding value.
    print('{}: {}'.format(item, value))

Sample Output:

exit_code: 0
node_version: 8.11.3
versioning: null
version: 0.0.0
unstable_restarts: 0
restart_time: 21
pm_id: 0
created_at: 1622456136302
axm_dynamic: [object Object]
axm_options: [object Object]
axm_monitor: [object Object]
axm_actions: 
pm_uptime: 1623107594098
status: launching
unique_id: 840ddab5-aa87-4cb5-ab04-16da1d9802f6
PM2_HOME: /root/.pm2
PM2_INTERACTOR_PROCESSING: true
PM2_DISCRETE_MODE: true
PM2_PROGRAMMATIC: true
PYTHONPATH: /trinket/python3
MPLBACKEND: module://trinket_backend
TERM: xterm
HOME: /root
LC_ALL: en_US.UTF-8
LANGUAGE: en_US:en
LANG: en_US.UTF-8
DEBIAN_FRONTEND: teletype
HOSTNAME: b0e45c20d4ca
PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
NODE_APP_INSTANCE: 0
vizion_running: false
km_link: false
pm_pid_path: /root/.pm2/pids/shell-0.pid
pm_err_log_path: /dev/null
pm_out_log_path: /dev/null
exec_mode: fork_mode
instances: 1
exec_interpreter: node
pm_cwd: /trinket-workdir
pm_exec_path: /trinket-workdir/server/python3/shell.js
node_args: 
name: shell
env: [object Object]
merge_logs: true
vizion: true
autorestart: true
instance_var: NODE_APP_INSTANCE
pmx: true
automation: true
treekill: true
username: root
windowsHide: true
kill_retry_time: 100

Flowchart:

Python Code Editor:

Previous: Write a Python program to print to stderr.
Next: Write a Python program to get the current username.