system
system("command",arg0,arg1 ...) 执行命令返回结束状态
exec
The exec function executes a system command and never returns; use system instead of exec if you want it to return. It fails and returns false only if the command does not exist and it is executed directly instead of via your system's command shell (see below).
readpipe
The collected standard output of the command is returned. In scalar context,it comes back as a single (potentially multi-line) string. In list context,returns a list of lines (however you've defined lines with $/ or $INPUT_RECORD_SEParaTOR ).
返回运行结果
my $result = readpipe("ls -l");
print $result;
