谁能举个例子说明一下system和exec的区别嘛？

edwardhayes

rt

777

主要不同在它们的返回值上：

2. system (LIST)
4. Category: Process
5. Return Value: SCALAR, the exit code of the system command that was executed.
6. Definition: Executes LIST as an operating system call. The process to execute this command is forked and the script waits for the child process to return.
8. Note
10.     To capture the output from a system call use a back-quoted string instead of system().
12. system("ls -F /var > /tmp/t.tmp");

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2. exec (LIST)
4. Category: Process
5. Return Value: None.
6. Definition: This fuNCtion passes control from the script to an external system command. There is no return from this call. Note that system() calls external commands and does return.
8. exec("cat /etc/motd");

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libinary

exec会用新程序替代本进程

tx-cary

最初由 libinary 发表
exec会用新程序替代本进程

哦？是吗，那exec后面的代码就无用了？

libinary

最初由 tx-cary 发表
哦？是吗，那exec后面的代码就无用了？

除非exec调用出错，否则后面的代码不会执行，
所以一般exec后面的代码都是错误处理
另外，你应该看看fork，一般exec都和fork一起用