Questions tagged [stdio]

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How to pipe STDIO from a thread process to /dev/null?

I am trying to run Plarium Play with wine, but have encountered an odd issue. When trying to launch it from a regular desktop entry, I get this JavaScript error: This does not happen if I launch from ...
TheLabCat's user avatar
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Can I use KVM without ioctl?

Recently I've discovered how /dev/kvm doesn't seem to implement functionality for read() or write(), and any attempt to invoke them always results in Error 22 (Invalid argument). I'm trying to avoid ...
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Which commands need prefixing by "stdbuf"?

When I have a long running Bash pipeline of commands, and I often can't see any signs of life due to I/O buffering. I found online that buffering can be disabled using stdbuf. An example shown here ...
user2153235's user avatar
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Unexpected behavior of linux specific getline() function in C

#include <stdio.h> #include <stdlib.h> #define MAXLEN 1024 void reverse(FILE *, FILE *); int main(int argc, char ** argv) { ... reverse(fptr, stdout); ... return 0; } void ...
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How `stdio` recognizes whether the output is redirected to the terminal or a disk file? [duplicate]

#include <stdio.h> #include <unistd.h> int main(void) { printf("If I had more time, \n"); write(STDOUT_FILENO, "I would have written you a shorter letter.\n", 43); ...
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How to access kallsyms from outside operational system (edk2 SMM driver)?

I'm using EDK2 to write a System Management Mode (SMM) driver. I think it uses "Pure C", given the fact that I'm not able to use standard C library like stdio. Even if I #include <stdio.h&...
Allan Almeida's user avatar
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How to escape standard input when "cat f - g" [duplicate]

man cat shows the following example: cat f - g Output f's contents, then standard input, then g's contents. How do you escape the standard input and proceed to output the 2nd ...
MattP's user avatar
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*nix shell: How to disable pipe buffering for ALL pipes in a command?

I want every pipe to be unbuffered, so I don't have to type stdbuf -oL for every piped command. When concocting commands with multiple pipes, it would be nice if there was a environment variable or ...
Aaron Frantisak's user avatar
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2 answers
197 views

Unexpected expect/ssh question

I am seeking to automate ssh password based logins (and a series of actions after logging in). I am aware that the ssh password prompt bypasses STDIN. To that end I put together a quick expect script. ...
symcbean's user avatar
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3 votes
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Additional file descriptor for debugging and piped output (logging, metrics, etc)

For a bash script project, I write human-readable log info to stdout/stderr. Additionally, I want to write formatted metrics to a third stream that will be discarded by default but can be redirected ...
Mazzen's user avatar
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Did fwrite/fread(3) offer different "multiple items" behavior on different platforms historically?

The fread(3) and fwrite(3) have an extra parameter for a variable number of items. So a typical write often has a hardcoded count when all it has is a char buffer to begin with e.g. fwrite(data, len, ...
natevw's user avatar
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2 answers
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How to read server stdout and continue only after message is outputted

Say I have a simple Node.js server like: const http = require('http'); const server = http.createServer((req,res) => res.end('foobar')) server.listen(3000, () => { console.log(JSON....
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2 answers
869 views

Appending both stdout and stderr to file

I have this: nohup_ntrs(){ nohup_file="$HOME/teros/nohup/stdio.log" mkdir -p "$(dirname "$nohup_file")"; echo " ------------- BEGIN $(date) -------------- " >> "$nohup_file" nohup "$@" &...
Alexander Mills's user avatar
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How to determine if a process is part of a pipeline (producer in pipeline)? [duplicate]

So if I am in my terminal and run: $ my_proc | grep foo in my_prof I know it's part of a pipeline because stdout is not attached to the terminal but to grep. On the other hand, if I just run this: $...
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1 answer
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Writing and Executing Program to behave like console

I have written a set of programs with the intent of using a radio transmitter-receiver (NRF24L01) to connect two devices as if they were connected via a serial interface. Currently, i am able to ...
fisherdog1's user avatar
4 votes
1 answer
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Determine if producer is outpacing consumer in pipeline

If I have: node foo.js | node bar.js is there a way to determine if there is a queue in between them that's building up? in other words if the producer is outpacing the consumer w.r.t. stdio?
Alexander Mills's user avatar
7 votes
3 answers
9k views

Behaviour of the backspace on terminal

This is about the behaviour of the backspace (\b) character.  I have the following C program: int main() { printf("Hello\b\b"); sleep(5); printf("h\n"); return 0; } The output on my ...
forumulator's user avatar
7 votes
3 answers
6k views

Communicate backwards in a pipe

I have a simple pipeline: node foo.js | node bar.js bar.js will read from stdin to get data from foo.js. But what I want to do is ensure that bar.js gets one of the last messages from foo.js before ...
Alexander Mills's user avatar