PHP
Environment management
Learn to manage environment variables with a .env file and getenv().
Environment variables
Environment variables separate configuration from code: database passwords, API keys and debug flags do not get baked into the source.
In PHP you read a single variable with getenv('APP_ENV'); the $_ENV superglobal holds them all. putenv('KEY=value') defines a new one.
A .env file holds KEY=VALUE lines; you can load it as an array with parse_ini_file.
Parsing the .env file
parse_ini_file('.env') reads the file and returns an associative array like ['APP_ENV' => 'production', 'DEBUG' => '0']. Lines starting with # count as comments.
To push values into $_ENV you assign $_ENV[$key] = $val; then you read from the superglobal directly instead of getenv.
In production the .env file is never committed; it is placed on the server during deploy. An accidental commit leaks secrets.
Exercise Generate and parse .env
Generate a .env file with PHP: write APP_ENV=production and DEBUG=0 lines via file_put_contents. Then read it back with parse_ini_file and print each key/value pair as KEY=value.
Show example solution
First write the file with file_put_contents(".env", "APP_ENV=production\nDEBUG=0\n");. Then read with $env = parse_ini_file(".env");. Print with foreach ($env as $key => $val) { echo $key . "=" . $val . "\n"; }.
Example solution:
<?php
// Generate and parse .env
file_put_contents(".env", "APP_ENV=production\nDEBUG=0\n");
$env = parse_ini_file(".env");
foreach ($env as $key => $val) {
echo $key . "=" . $val . "\n";
}
Test yourself
-
Complete the getenv call
<?php
$env = ____('APP_ENV');
print_r(["env" => $env]);
Show answer
<?php
$env = getenv('APP_ENV');
print_r(["env" => $env]);
-
Match the environment tools
- getenv
- Reads one variable
- $_ENV
- Superglobal array
- parse_ini_file
- Reads a file
- putenv
- Defines a variable
-
Which function loads a .env file as an array?
- file_get_contents
- parse_ini_file
- fopen
- require
Show answer
parse_ini_file — Correct. parse_ini_file turns the .env file into a KEY => VALUE array.
Next lesson: Zero-downtime deployment
