Online PHP editor | output for udZRH

Output for 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6: Warning: system(): Unable to fork [which perl] in /in/udZRH on line 2 array(1) { [0]=> string(10) "./dev/fd/3" }
Output for 7.4.26 - 7.4.32, 8.0.14 - 8.0.30: Warning: system(): Unable to fork [which perl] in /in/udZRH on line 2 bool(false)
Output for 5.2.3 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.25, 7.4.33, 8.0.0 - 8.0.13: Warning: system(): Unable to fork [which perl] in /in/udZRH on line 2 array(4) { [0]=> string(10) "./dev/fd/0" [1]=> string(10) "./dev/fd/1" [2]=> string(10) "./dev/fd/2" [3]=> string(10) "./dev/fd/3" }
Output for 4.4.3 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.2: Warning: system() [<a href='function.system'>function.system</a>]: Unable to fork [which perl] in /in/udZRH on line 2 array(0) { }
Output for 4.3.2 - 4.3.6, 4.3.9 - 4.3.11, 4.4.0 - 4.4.2: Warning: system(): Unable to fork [which perl] in /in/udZRH on line 2 array(0) { }
Output for 4.3.7 - 4.3.8: Warning: system(): Unable to fork [which perl] in /in/udZRH on line 2 bool(false)
Output for 4.3.0 - 4.3.1: Warning: system() [<a href='http://www.php.net/function.system'>function.system</a>]: Unable to fork [which perl] in /in/udZRH on line 2 array(0) { }