PHP script not getting exec() result?

Question

linux

I wrote a php script to make life easier, for example there is such a command: When I run the script from the console, everything works and $result is filled with output. When I put the script on cron $result empty, I tried something for a solution, nothing helped.
exec("hdparm -t /dev/disk/by-$uuid", $result);

Answer 1

As the documentation for exec says , in the notes section

Note:
If you are going to use this function in a program running as a daemon, make sure that the standard output of the function is directed to a file or other stream, otherwise PHP will hang until the end of the program.

Note:
On Windows, the exec() function starts cmd.exe to run the command. If you want to run an external program without running cmd.exe, then use the proc_open() function with the bypass_shell option set.