PHPsystem ("ls-l", $ ret_var) returns 127 of the execution result

The execution result of PHPsystem (ls-l, $ ret_var) is 127. dear friends, the younger brother recently installed a lighttpd on the ARm board and configured PHP5.4, however, when I write a php file to call a local executable file, the returned value is 127, which is an error return value that does not find the command, now I am talking about how to put the test program C test in the directory/usr/bin where the local program can be executed by default. the system still returns the 127, absolute path, and the relative path has been tried, put PHP. you cannot see the error when debugging INI. You have also tried to modify the permissions of folders and files 755. What should I modify in PHP. INI. The safe_mode and with-exec-dir options are not available in version 5.4. thank you for your advice.

Reply to discussion (solution)

See
1. exec ()-Execute an external program
2. passthru ()-Execute an external program and display raw output
3. popen ()-open the process file pointer
4. escapeshellcmd ()-Escape shell metacharacters
5. pcntl_exec ()-execute the specified program in the current process space
6. backtick operator

? Warranty ?? :
1. php. ini? Is it disabled? Listed? Line letter?
2. quilt? The row file owner is the same as the php file owner.
3. quilt? Must the row file have 07xx? Limited

Is this problem solved?