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Questions tagged [stderr]

The standard error output stream (stderr) is typically used by a program to output error messages or diagnostics.

The standard error stream, stderr, is a stream typically used by a program to output error or diagnostic messages. It is one of the three standard streams used by a UNIX-like program, along with and .

Like , stderr is outputted to the text terminal unless redirected.

The file descriptor for standard output is 2 (two); the POSIX definition is STDERR_FILENO.

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Capture program stdout and stderr to separate variables

Is it possible to redirect stdout from an external program to a variable and stderr from external programs to another variable in one run? For example: $global:ERRORS = @(); $global:PROGERR = @(); function test() { # Can we redirect errors to…
dusz
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How is STDERR.puts different from puts in Ruby?

I'm learning the language from Programming Ruby 1.9, and they toss STDERR.puts into a block of code early in the book without explaining why they're using it or how it's different from puts. I've googled and wikied the term, but all I can gather…
rubynewbie
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Merging a Python script's subprocess' stdout and stderr while keeping them distinguishable

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…
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Redirect subprocess stderr to stdout

I want to redirect the stderr output of a subprocess to stdout. The constant STDOUT should do that, shouldn't it? However, $ python >/dev/null -c 'import subprocess;\ subprocess.call(["ls",…
phihag
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"subprocess.Popen" - checking for success and errors

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…
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Making curl send errors to stderr and everything else to stdout

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

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

I'd like to temporarily redirect stderr in a Ruby script for the duration of a block, ensuring that I reset it to its original value at the end of the block. I had trouble finding how to do this in the ruby docs.
horseyguy
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How can I display a 'naked' error message in PowerShell without an accompanying stacktrace?

How can I write to standard error from PowerShell, or trap errors such that: An error message is displayed as an error (truly writing to standard error so that TeamCity and Octopus see it as an error) No stack trace garbage muddles my beautiful,…
Peter Seale
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Run ffmpeg without outputting configuration information?

I'm invoking ffmpeg with subprocess.Popen, and trying to capture the stderr output and write it to logging. args = ['ffmpeg', '-i', path] if start: args += ['-ss', start] if end: args += ['-t', end] args += [ '-vcodec', 'copy', …
Matt Joiner
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multiprocessing: How can I ʀᴇʟɪᴀʙʟʏ redirect stdout from a child process?

NB. I have seen Log output of multiprocessing.Process - unfortunately, it doesn't answer this question. I am creating a child process (on windows) via multiprocessing. I want all of the child process's stdout and stderr output to be redirected to a…
Tom
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Should I output warnings to STDERR or STDOUT?

I'm making a script that handles a predefined set of data, outputting to a file. I want to pop up a warning when one datum (which is always "Regular" in every set that I've had access to) is different stating that this value is unhandled (since I…
Stuart P. Bentley
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What method should I use to write error messages to 'stderr' using 'printf' in a bash script?

I want to direct the output of a printf in a bash script to stderr instead of stdout. I am not asking about redirecting either stderr or stdout from where ever they are currently routed. I just want to be able to send the output from a printf to…
irrational John
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What are "cerr" and "stderr"?

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…
Russel
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How to Pipe Output to a File When Running as a Systemd Service?

I'm having trouble piping the STDOUT & STDERR to a file when running a program as a systemd service. I've tried adding the following to the .service file: ExecStart=/apppath/appname > /filepath/filename 2>&1 But this doesn't work. The output is…
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