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How do I redirect stderr and stdout to file for a Ruby script?

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How do I redirect stderr and stdout to file for a Ruby script? Mark Rushakoff From within a Ruby script , you can redirect stdout and stderr with the IO#reopen method. # a.rb $stdout.reopen("out.txt", "w") $stderr.reopen("err.txt", "w") puts 'normal output' warn 'something to stderr' $ ls a.rb $ ruby a.rb $ ls a.rb err.txt out.txt $ cat err.txt something to stderr $ cat out.txt normal output Note: reopening of the standard streams to /dev/null is a good old method of helping a process to become a daemon. For example: # daemon.rb $stdout.reopen("/dev/null", "w") $stderr.reopen("/dev/null", "w")

Standard input and output units in Fortran 90?

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问题 How can I read and write to the standard input, output and error streams stdin , stdout and stderr in Fortran? I've heard writing to stderr , for example, used to be write(5, fmt=...) , with 5 the unit for stderr , and I know the way to write to stdout is to use write(*, fmt=...) . How do I read and write to the standard input and output units with the ifort compiler? Compiler version: Intel(R) Fortran Compiler for applications running on Intel(R) 64, Version 10.0 Build 20070426 Package ID: l

How to capture stdout/stderr with googletest?

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问题 Is it possible to capture the stdout and stderr when using the googletest framework? For example, I would like to call a function that writes errors to the console (stderr). Now, when calling the function in the tests, I want to assert that no output appears there. Or, maybe I want to test the error behaviour and want to assert that a certain string gets printed when I (deliberately) produce an error. 回答1: I have used this snippet before to redirect cout calls to a stringstream when testing

log syntax errors and uncaught exceptions for a python subprocess and print them to the terminal

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问题 The Problem I've been trying to write a program that logs uncaught exceptions and syntax errors for a subprocess. Easy, right? Just pipe stderr to the right place. However , the subprocess is another python program- I'll call it test.py - that needs to run as if its output/errors are not being captured. That is, running the logger program needs to seem like the user has just run python test.py as normal. Further complicating the issue is the problem that raw_input actually gets sent to stderr

Redirect all output to file using Bash on Linux? [duplicate]

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问题 This question already has an answer here: How to redirect and append both stdout and stderr to a file with Bash? 7 answers I am trying to redirect all output from a command line programme to a file. I am using Bash. Some of the output is directed to a the file, but some still appears in the terminal and is not stored to the file. Similar symptoms are described here: Redirect all output to file However I have tried the proposed solution (capture stderr) without success: <cmd> <args> > stdout

“subprocess.Popen” - checking for success and errors

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I want to check if a subprocess has finished execution successfully or failed. Currently I have come up with a solution but I am not sure if it is correct and reliable. Is it guaranteed that every process outputs its errors only to stderr respectfully to stdout : Note: I am not interested in just redirecting/printing out the output. That I know already how to do. pipe = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True) if "" == pipe.stdout.readline(): print("Success") self.isCommandExectutionSuccessful = True if not "" == pipe.stderr.readline():

When should I use perror(“…”) and fprintf(stderr, “…”)?

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问题 Reading the man pages and some code did not really help me in understanding the difference between - or better, when I should use - perror("...") or fprintf(stderr, "...") . 回答1: Calling perror will give you the interpreted value of errno , which is a thread-local error value written to by POSIX syscalls (i.e., every thread has it's own value for errno ). For instance, if you made a call to open() , and there was an error generated (i.e., it returned -1 ), you could then call perror

Making curl send errors to stderr and everything else to stdout

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问题 Is there a way to tell curl to output errors to stderr, and everything else to stdout? The reason is that I am using curl from the command line (actually a cronjob) to upload a file to an FTP site every evening. Unfortunately because curl outputs status information on stderr, I receive an e-mail about an error when nothing actually went wrong. (I'm redirecting stdout to a log file, but leaving stderr unchanged so that cron will e-mail it to me if there is any output.) There are options to

How to replicate tee behavior in Python when using subprocess?

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I'm looking for a Python solution that will allow me to save the output of a command in a file without hiding it from the console. FYI: I'm asking about tee (as the Unix command line utility) and not the function with the same name from Python intertools module. Details Python solution (not calling tee , it is not available under Windows) I do not need to provide any input to stdin for called process I have no control over the called program. All I know is that it will output something to stdout and stderr and return with an exit code. To work when calling external programs (subprocess) To

Capture both stdout and stderr in Bash [duplicate]

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This question already has an answer here: Capture stdout and stderr into different variables 13 answers I know this syntax var=`myscript.sh` or var=$(myscript.sh) Will capture the result ( stdout ) of myscript.sh into var . I could redirect stderr into stdout if I wanted to capture both. How to save each of them to separate variables? My use case here is if the return code is nonzero I want to echo stderr and suppress otherwise. There may be other ways to do this but this approach seems it will work, if it's actually possible. zb' There is no way to capture both without temp file. You can