stderr

I'm having trouble figuring out how to both echo to the standard error stream and redirect the error stream of an executable. I have come from a Bourne shell and Korn shell background, of which I would use; # Write to stderr echo "Error Message!" >&2 # Redirect stderr to file /do/error 2>/tmp/err.msg Use Write-Error to write to stderr. To redirect stderr to file use: Write-Error "oops" 2> /temp/err.msg or exe_that_writes_to_stderr.exe bogus_arg 2> /temp/err.msg Note that PowerShell writes errors as error records. If you want to avoid the verbose output of the error records, you could write out

In Ruby, what is the difference between $stdout (preceded by a dollar sign) and STDOUT (in all caps)? When doing output redirection, which should be used and why? The same goes for $stderr and STDERR . Edit: Just found a related question . Brian $stdout is a global variable that represents the current standard output. STDOUT is a constant representing standard output and is typically the default value of $stdout . With STDOUT being a constant, you shouldn't re-define it, however, you can re-define $stdout without errors/warnings (re-defining STDOUT will raise a warning). for example, you can

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. mossman tsk = subprocess.Popen(args,stdout=subprocess.PIPE,stderr=subprocess.STDOUT) subprocess.STDOUT is a special flag that tells subprocess to route all stderr output to stdout, thus combining your two streams.

大部分在 crontab 计划任务中都会年到未尾带 >/dev/null 2>&1,是什么意思呢？ > 是重定向 /dev/null 代表空设备文件 1 表示stdout标准输出,系统默认值是1,所以 ">/dev/null" 等同于 "1>/dev/null" 2 表示stderr标准错误 & 表示等同于的意思,2>&1,表示2的输出重定向等同于1 整句的意思就是标准输出重定向到空设备文件,也就是不输出任何信息到终端,标准错误输出重定向等同于标准输出,因为之前标准输出已经重定向到了空设备文件,所以标准错误输出也重定向到空设备文件 command > file 2>file 与 command > file 2>&1 有什么区别呢? command > file 2>file 的意思是将命令所产生的标准输出信息,和错误的输出信息送到file 中.command > file 2>file 这样的写法,stdout和stderr都直接送到file中, file会被打开两次,这样stdout和stderr会互相覆盖,这样写相当使用了FD1和FD2两个同时去抢占file 的管道. 而command >file 2>&1 这条命令就将stdout直接送向file, stderr 继承了FD1管道后,再被送往file,此时,file 只被打开了一次,也只使用了一个管道FD1

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 subject to the normal means of redirection. I am using a Windows 7 cmd.exe console window. None of these

We're trying to debug some cURL errors on the server, and I would like to see the STDERR log. Currently, all we can see for our error is "error code: 7" and that we can't connect to target server. We have contacted the host and made special rule to open the port we need and we're even ignoring the certificate for the time being. Still, we can't connect. I need to debug this, but I can't see any pertinent information on my end. The lines mentioning "VERBOSE" and "STDERR" are the most important, I think. Nothing is written to $curl_log. What am I doing wrong? Following the manuals logic, this

How do you print to stderr in R ? This would especially useful for scripts written in Rscript . Actually the following works for me: write("prints to stderr", stderr()) write("prints to stdout", stdout()) Here's a more flexible version for debugging/verbose use in Rscript. Not only it prints to stderr as you ask, but it also allows you to pass variable number of arguments, types etc, like printf does. v <- function(...) cat(sprintf(...), sep='', file=stderr()) Now one can do things like: v("name: %s age: %d\n", name, age) etc. Is it possible to configure the print function to print to stderr?