É importante desabilitar algumas funções do PHP, por questão de segurança:
Abra o arquivo no seu editor favorito:
pico /usr/lib/php.ini
Lozalize a linha: disable_functions = e insira:
dl, system, exec, shell_exec, chown, chgrp, escapeshellcmd, puten, popen, pclose, passthru, proc_open, proc_get_status, proc_nice, proc_close, proc_terminate, posix_ctermid, posix_get_last_error, posix_getcwd, posix_getegid, posix_geteuid, posix_getgid, posix_getgrgid, posix_getgrnam, posix_getgroups, posix_getlogin, posix_getpgid, posix_getpgrp, posix_getpid, posix_getppid, posix_getpwnam, posix_getpwuid, posix_getrlimit, posix_getsid, posix_getuid, posix_isatty, posix_kill, posix_mkfifo, posix_setegid, posix_seteuid, posix_setgid, posix_setpgid, posix_setsid, posix_setuid, posix_strerror, posix_times, posix_ttyname, posix_uname
salves e saia, após
service httpd restart
