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Copy STDOUT to file without stopping it showing onscreen

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问题 The program I am making is designed to be run unattended, because of this I have redirected the stdout and stderr streams to a log file. While this works without any problems, while I am still making and debugging the software I would like it to show on the screen as well. Is this possible? To redirect the streams I have used System.setErr(logWriter); System.setOut(logWriter); Thanks. 回答1: a bit crude perhaps, but you could try this: private static final isDebugMode = true; ... if (

How can I run an external command and capture its output in Perl?

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问题 I'm new to Perl and want to know of a way to run an external command (call it prg ) in the following scenarios: Run prg , get its stdout only. Run prg , get its stderr only. Run prg , get its stdout and stderr , separately. 回答1: You can use the backtics to execute your external program and capture its stdout and stderr . By default the backticks discard the stderr and return only the stdout of the external program.So $output = `cmd`; Will capture the stdout of the program cmd and discard

Understanding stdin stdout stderr [duplicate]

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问题 This question already has an answer here: Confused about stdin, stdout and stderr? 10 answers I'm trying to understand stdin stdout and stderr . I see them used in people's code all the time and I can't understand exactly what they are. I am assuming that they have something to do with input/output but have been searching for an explanation online and can't find one. Does anybody know of a good link with an explanation or if it is simple enough to explain it would be a great help to me. Since

Ubuntu下使用python实现全自动ssh免密登录设置

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Ubuntu下使用python实现全自动ssh免密登录设置本文主要是使用了python自带的模块os和第三方的模块paramiko,实现在知道用户名和密码的情况下，将ssh远程连接设置为免密登录的形式。本质就是为要登录的主机添加公钥，本机添加私钥。当然一切的前提是你已经开启了ssh服务。这个函数也可以嵌入的你的代码中，在需要ssh登录的地方提前设置好免登录，今后就可以不用再输密码了。本人在服务端的Ubuntu和centos上均测试通过。centos你可能需要修改一下sshd服务重启的指令。 import os, paramiko def ssh_authentication(server_ip, user, passwd): """进行ssh的免密码认证""" # server_id 备份服务器地址，字符串 logger.info("test ping server %s ..." % server_ip) if os.system("ping %s -c 3 >>/dev/null" % server_ip): # 先测试一下连通性 return -1 if os.path.exists(os.path.expanduser("~/.ssh/id_rsa")) and os.path.exists( os.path.expanduser("~/.ssh/id_rsa.pub

Merging a Python script's subprocess' stdout and stderr while keeping them distinguishable

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问题 I would like to direct a python script's subprocess' stdout and stdin into the same file. What I don't know is how to make the lines from the two sources distinguishable? (For example prefix the lines from stderr with an exclamation mark.) In my particular case there is no need for live monitoring of the subprocess, the executing Python script can wait for the end of its execution. 回答1: tsk = subprocess.Popen(args,stdout=subprocess.PIPE,stderr=subprocess.STDOUT) subprocess.STDOUT is a special

Bash how do you capture stderr to a variable? [duplicate]

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This question already has an answer here: Bash script - store stderr in a variable [duplicate] 4 answers Bash how do you capture stderr to a variable? I would like to do something like this inside of my bash script sh -c path/myExcecutable-bin 2>&1 =MYVARIABLE How do you send stderror output to a variable ? Tim Pote To save both stdout and stderr to a variable: MYVARIABLE="$(path/myExcecutable-bin 2>&1)" Note that this interleaves stdout and stderr into the same variable. To save just stderr to a variable: MYVARIABLE="$(path/myExcecutable-bin 2>&1 > /dev/null)" 来源： https://stackoverflow.com

C连接mysql【转】

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原文： http://www.cnblogs.com/wangkangluo1/archive/2012/07/01/2571800.html mysql 使用的是xampp 需要指定sock 源码：main.c #if defined(_WIN32) || defined(_WIN64) // 为了支持windows平台上的编译 #include <windows.h> #endif #include <stdio.h> #include <stdlib.h> #include <mysql/mysql.h> // 我的机器上该文件在/usr/local/include/mysql下 // 定义数据库操作的宏，也可以不定义留着后面直接写进代码 #define SELECT_QUERY "select username from test where userid = %d" int main( int argc, char **argv) // char **argv 相当于 char *argv[] { MYSQL mysql, *sock; // 定义数据库连接的句柄，它被用于几乎所有的MySQL函数 MYSQL_RES *res; // 查询结果集，结构类型 MYSQL_FIELD *fd ; // 包含字段信息的结构 MYSQL_ROW row ; //

Python: How to get stdout after running os.system?

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I want to get the stdout in a variable after running the os.system call. Lets take this line as an example: batcmd="dir" result = os.system(batcmd) result will contain the error code ( stderr 0 under Windows or 1 under some linux for the above example). How can I get the stdout for the above command without using redirection in the executed command? If all you need is the stdout output, then take a look at subprocess.check_output() (added in Python 2.7): import subprocess batcmd="dir" result = subprocess.check_output(batcmd, shell=True) Because you were using os.system() , you'd have to set

Why do System.err statements get printed first sometimes?

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问题 In Java, I noticed that sometimes, System.err statements get printed first before System.out statements, although the latter appears first before the former in my code. Why? I'm curious. 回答1: Typically, System.out is a buffered output stream, so text is accumulated before it is flushed to the destination location. This can dramatically improve performance in applications that print large amounts of text, since it minimizes the number of expensive system calls that have to be made. However, it

Utility with unredirectable output (Windows)

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问题 I am using a Microsoft command-line utility to perform a task. The specific details of what the utility does and the task it performs are, I think, relatively unimportant. This is what is important: The command-line utility emits text to the console window. I cannot figure out how to redirect this text to a file, though I have tried every approach I could find through research. It seems the utility is using some strange OS function call that causes text to be printed in a way that is not