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I'm trying to use popen() to catch the stderr of a call, but of course it doesn't seem to be doing that. Any ideas? My code looks more or less like this: popen("nedit", "r"); But I'm getting all this garbage about non-utf8 on my screen... popen gives you a file handle on a process' stdout, not its stderr. Its first argument is interpreted as a shell command, so you can do redirections in it: FILE *p = popen("prog 2>&1", "r"); or, if you don't want the stdout at all, FILE *p = popen("prog 2>&1 >/dev/null", "r"); (Any other file besides /dev/null is acceptable as well.) If you want to discard

I have a python subprocess that I'm trying to read output and error streams from. Currently I have it working, but I'm only able to read from stderr after I've finished reading from stdout . Here's what it looks like: process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE) stdout_iterator = iter(process.stdout.readline, b"") stderr_iterator = iter(process.stderr.readline, b"") for line in stdout_iterator: # Do stuff with line print line for line in stderr_iterator: # Do stuff with line print line As you can see, the stderr for loop can't start until the stdout loop

there has been many previous questions about redirecting stdout/stderr to a file. is there a way to redirect stdout/stderr to a string? Yes, you can redirect it to an std::stringstream : std::stringstream buffer; std::streambuf * old = std::cout.rdbuf(buffer.rdbuf()); std::cout << "Bla" << std::endl; std::string text = buffer.str(); // text will now contain "Bla\n" You can use a simple guard class to make sure the buffer is always reset: struct cout_redirect { cout_redirect( std::streambuf * new_buffer ) : old( std::cout.rdbuf( new_buffer ) ) { } ~cout_redirect( ) { std::cout.rdbuf( old ); }

This question already has an answer here: How to store standard error in a variable 15 answers I'm writing a script to backup a database. I have the following line: mysqldump --user=$dbuser --password=$dbpswd \ --host=$host $mysqldb | gzip > $filename I want to assign the stderr to a variable, so that it will send an email to myself letting me know what happened if something goes wrong. I've found solutions to redirect stderr to stdout, but I can't do that as the stdout is already being sent (via gzip) to a file. How can I separately store stderr in a variable $result ? Try redirecting stderr

进击のpython 网络编程——粘包现象 前面我们提到了套接字的使用方法，以及相关bug的排除 还记得我们提到过一个1024吗？ 我们现在要针对这个来研究一下一个陷阱 在研究这个陷阱之前我要先教你几条语句 这是windows的命令啊 ipfonfig 查看本地网卡的ip地址 dir 查看某一个文件夹下的子文件名和子文件夹名 tasklist 查看运行的进程 那我这三条命令怎么执行呢？？直接敲？？ 好像没什么用，所以说我需要打开我的cmd窗口来键入这些命令 而cmd也就是一个能把特殊的字母组合执行出来的一个程序而已 当我在cmd里键入dir的时候得到的就是这些东西 那我想在编译器里搞这个东西呢？ 哦！第一反应就是os模块 import os os.system("dir") 就执行起来了吧 那我这算是拿到结果了吗? 我觉得不算,为什么? 咱们想要达到的效果是我在客户端输入一个dir发送给服务端,服务端给我返回这一堆东西才叫拿到结果了是吧 import os res = os.system("dir") print(f"返回的结果是:{res}") 那结果我打印的是什么呢??是0!那为什么是这个呢? 这个0是代表这个命令是不是成功 如果返回的是0,就是成功了,如果是非零,就是失败了! 所以说他返回的是一个是否成功执行语句的状态,而不是执行语句的返回结果 那os模块就被pass掉了

一、Socket（套接字） ★注意点： ① 127.0.0.1本机地址回环：只能识别自己，其他人无法访问 ② send与recv对应，不要出现两边是相同的情况，recv是跟内存要数据，无需考虑 ③ tcp特点是会将数据量比较小的并且时间间隔比较短的数据，一次性打包发送给对方 1 import socket 2 3 server = socket.socket() # 买手机 不传参数默认用的就是TCP协议 4 server.bind(('127.0.0.1',8080)) # bind((host,port)) 插电话卡 绑定ip和端口 5 server.listen(5) # 开机 半连接池 6 7 conn, addr = server.accept() # 接听电话 等着别人给你打电话 8 data = conn.recv(1024) # 听别人说话 接收1024个字节数据 9 conn.send(b'hello baby~') # 给别人回话 10 11 conn.close() # 挂电话 12 server.close() # 关机 Server端代码 1 import socket 2 3 client = socket.socket() # 拿电话 4 client.connect(('127.0.0.1',8080)) # 拨号 写的是对方的ip和port 5 6