Why doesn't exec(“top”); work on Linux?

Question

I was trying to execute this command

echo exec(\"top\");

and

echo exec(\"/usr/bin/top\");

neither works

Answer 1

You actually can call top and echo its output. Code that worked for me:

passthru('/usr/bin/top -b -n 1');

-b - running in batch mode

-n 1 - only one iteration