What is different between exec(), shell_exec, system() and passthru() functions in PHP? [duplicate]

• exec only returns the last line of the generated output.
• shell_exec returns the full output of the command, when the command finished running.
• system immediately shows all output, and is used to show text.
• passthru also returns output immediately, but is used for binary data. passthru displays raw data.

With both exec and shell_exec it is possible to handle the output yourself, while system and passthru won’t let you customize it and immediately display the output.

A more detailed comparison can be found here.