erlang调用外部程序如何得到其退出状态

转载请注明，来自：http://blog.csdn.net/skyman_2001

经常会有erlang程序调用外部程序的需求，比如调用shell命令程序，一般是用os:cmd/1，比如：

1> erlang:open_port({spawn, "erlc"}, [exit_status]).#Port<0.573>2> flush().Shell got {#Port<0.573>,{exit_status,0}}ok3> erlang:open_port({spawn, "erlc a.erl"}, [exit_status]).#Port<0.584>4> flush().                                               Shell got {#Port<0.584>,{data,"a.erl:none: no such file or directory\n"}}Shell got {#Port<0.584>,{exit_status,1}}ok

When the external process connected to the port exits, a message of the form {Port,{exit_status,Status}} is sent to the connected process, where Status is the exit status of the external process. If the program aborts, on Unix the same convention is used as the shells do (i.e., 128+signal).