stderr

Get both STDOUT and STDERR of a program or script to a variable in perl [duplicate]

由 这一生的挚爱 提交于 2019-12-23 04:28:17
问题 This question already has answers here : How can I get the CPU time for a perl system call? (3 answers) Closed 2 years ago . I did lot of google to redirect the both STDOUT and STDERR of a program to a variable in perl, Initially i tried using both open and backticks , but failed to capture Error signal to the variable. I am posting this question because Now I got the solution and hope it may helps others.. 回答1: To get both STDOUT and STDERR into a variable use following code snippet using

What to do with unneeded streams from an external process?

由 家住魔仙堡 提交于 2019-12-23 03:12:31
问题 When I execute a command in a separate process, for example by using the Runtime.getRuntime().exec(...) method, whose JavaDoc states: Executes the specified command and arguments in a separate process. What do I need to do with the streams from this process, knowing that the process shall live until the Java program exists? (this is a detail but the Java program takes care of killing this process and the process itself has a safety built-in where it kills itself should it notice that the Java

13 Process Lifecycle: Process Creation and Termination

由 ぃ、小莉子 提交于 2019-12-23 00:34:09
1 Unix Processes 1.OS决定哪个进程在何时使用CPU 2 The Death of a Process 1.在 main 中终断自己 2.1 exit() and _exit() and _Exit() 三种终断进程的方法 方法|描述 –|-- _exit()|请求OS立刻终断进程,强行,不回收资源 exit()|C标准库函数,先回收资源,再终断 _Exit()|C标准库函数,本质是 _exit() 的包装 图片解释 _exit 绿色直接退出 exit 红色,回收I/O,等后才调用 _exit 2.2 I/O Buffering and Exit Procedures 1.左图 exit 会先将buffer里的内容输出的屏幕,再退出 2.右图 _exit 不会等待,直接退出 3.可以调用 fflush() 将buffer内容输出 2.3 Changing I/O Buffering policy 1.stdout and stdin is line buffered(标准输入和输出缓冲区遇到换行才会输出) 2.stderr is unbuffered(标准错误因为立刻输出,所以消耗资源会很大) 3.fully buffered,which means writes/reads occur once the buffer is full.

How can I redirect output to a boost log?

由 核能气质少年 提交于 2019-12-22 10:17:08
问题 I have a C++ program that uses boost log, and I load a user-provided dynamic link library. I'd like to redirect stderr to the boost log, so that anytime the user's library does: std::cerr << "Some stuff"; It produces the same result** as: BOOST_LOG_SEV(log,info) << "Some stuff"; Is this possible, and if so then how do I do it? (Also, I'm not sure what to do about the severity... since cerr << doesn't privide severity information. I'm open to suggestions on that as well...) ** By "same result"

Redirecting CGI error output from STDERR to a file (python AND perl)

由 ℡╲_俬逩灬. 提交于 2019-12-22 09:10:01
问题 I'm moving a website to Hostmonster and asked where the server log is located so I can automatically scan it for CGI errors. I was told, "We're sorry, but we do not have cgi errors go to any files that you have access to." For organizational reasons I'm stuck with Hostmonster and this awful policy, so as a workaround I thought maybe I'd modify the CGI scripts to redirect STDERR to a custom log file. I have a lot of scripts (269) so I need an easy way in both Python and Perl to redirect STDERR

How to ensure that we read all lines from boost::child process

由 和自甴很熟 提交于 2019-12-21 04:17:07
问题 I saw the following code on boost::child documentation page where they explain how to read the output of a child process. http://www.boost.org/doc/libs/1_64_0/doc/html/boost_process/tutorial.html They say after running your child process, we can read it via this loop:- bp::ipstream is; //reading pipe-stream bp::child c(bp::search_patk("nm"), file, bp::std_out > is); //then later while (c.running() && std::getline(is, line) && !line.empty()) data.push_back(line); I have 2 questions here :- If

Python: get output from a command line which exits with nonzero exit code

由 别来无恙 提交于 2019-12-21 02:41:58
问题 I am Using Python 2.7.1 on a Windows Server 2008 R2 x64 box. I'm trying to get the output of a command line process which gives a nonzero exit status after outputting the information I need. I was initially using subprocess.check_output , and catching the CalledProcessError which occurs with nonzero exit status, but while the returncode was stored in the error, no output revealed this. Running this against cases which give output but have an exit status of 0 works properly and I can get the

What are “cerr” and “stderr”?

由 旧街凉风 提交于 2019-12-20 17:36:28
问题 What is the difference between them and how are they used? Can anyone point me to examples? Specifically, how do you "write" to the stream in both cases and how do you recover and output (i.e. to the screen) the text that had been written to it? Also, the "screen" output is itself a stream right? Maybe I don't understand streams well enough. This can also be saved to a file of course, I know. Would all of these use fprintf / fscanf , etc? 回答1: cerr is the C++ stream and stderr is the C file

Redirecting stdout/stderr to multiple files

由 一笑奈何 提交于 2019-12-20 10:48:23
问题 I was wondering how to redirect stderr to multiple outputs. I tried it with this script, but I couldn't get it to work quite right. The first file should have both stdout and stderr, and the 2nd should just have errors. perl script.pl &> errorTestnormal.out &2> errorTest.out Is there a better way to do this? Any help would be much appreciated. Thank you. 回答1: perl script.pl 2>&1 >errorTestnormal.out | tee -a errorTestnormal.out > errorTest.out Will do what you want. This is a bit messy, lets

Python: subprocess.call, stdout to file, stderr to file, display stderr on screen in real time

由 给你一囗甜甜゛ 提交于 2019-12-20 08:20:34
问题 I have a command line tool (actually, several) that I am writing a wrapper for in Python. The tool is generally used like this: $ path_to_tool -option1 -option2 > file_out The user gets the output written to file_out, and is also able to see various status messages of the tool as it is running. I want to replicate this behavior, while also logging stderr (the status messages) to a file. What I have is this: from subprocess import call call(['path_to_tool','-option1','option2'], stdout = file
订阅 stderr