PHP CLI vs web server execution - Visual Side-by-Side Comparison

Concept Flow - PHP CLI vs web server execution

Start PHP Script

↓

Is script run via CLI?

Yes→Execute script in CLI mode

↓

Execute script in Web Server mode

↓

Output result

↓

End

The PHP script starts and checks if it runs in CLI or web server mode, then executes accordingly and outputs the result.

Execution Sample

PHP

<?php
if (php_sapi_name() == 'cli') {
    echo "Running in CLI mode\n";
} else {
    echo "Running in Web Server mode\n";
}
?>

This code prints whether PHP is running in CLI or web server mode.

Execution Table

Step	Action	php_sapi_name() Result	Condition (php_sapi_name() == 'cli')	Branch Taken	Output
1	Call php_sapi_name()	cli	True	CLI branch	Running in CLI mode
2	Print output	-	-	-	Running in CLI mode
3	End script	-	-	-	-

💡 Script ends after printing output based on execution mode.

Variable Tracker

Variable	Start	After Step 1	Final
php_sapi_name()	undefined	'cli'	'cli'
Output	empty	"Running in CLI mode\n"	"Running in CLI mode\n"

Key Moments - 3 Insights

Why does the script print "Running in CLI mode" when run from the command line?

Because php_sapi_name() returns 'cli' in CLI mode, making the condition true and selecting the CLI branch (see execution_table step 1).

What happens if the script runs through a web server?

php_sapi_name() returns a different string (like 'apache2handler'), so the condition is false and the else branch runs, printing "Running in Web Server mode".

Can the output differ if the script is run in different environments?

Yes, because php_sapi_name() detects the environment, changing the output accordingly (see variable_tracker for php_sapi_name() values).

Visual Quiz - 3 Questions

Look at the execution_table, what is the output at step 2 when running in CLI mode?

A No output

B Running in Web Server mode

C Running in CLI mode

D Error message

💡 Hint

Check the Output column at step 2 in the execution_table.

At which step does the script decide which mode it is running in?

A Step 3

B Step 1

C Step 2

D Before step 1

💡 Hint

Look at the Action and Condition columns in execution_table.

If php_sapi_name() returned 'apache2handler', what would the output be?

A Running in Web Server mode

B Running in CLI mode

C No output

D Script error

💡 Hint

Refer to key_moments about what happens when php_sapi_name() is not 'cli'.

Concept Snapshot

PHP scripts can run in two main ways: CLI (command line) or web server.
Use php_sapi_name() to detect mode.
If it returns 'cli', script runs in CLI mode.
Otherwise, it runs in web server mode.
Output or behavior can change based on this.
Useful for scripts that behave differently in each environment.

Full Transcript

This visual execution shows how PHP scripts detect if they run in CLI or web server mode using php_sapi_name(). The script starts, calls php_sapi_name(), and checks if it equals 'cli'. If yes, it prints 'Running in CLI mode'; otherwise, it prints 'Running in Web Server mode'. Variables and output change accordingly. This helps scripts adapt to different environments.