stderr

问题 How can I print the stderr output of pv to a file? For example: timeout 5s dd if=/dev/random | pv -r > /dev/null [ 505kiB/s] The rate line output is "updated" over the course of my five second timeout. I tried this but it does not work (log is empty): timeout 5s dd if=/dev/random | pv -r > /dev/null 2> rates.log I believe it has something to do with carriage returns in the stderr output, but after an hour I am stuck. Ideally my log file would have multiple lines each time pv prints a new

问题 I'll try to be much clear as possible. I have a very simple test script that control a Power Supply, the script measure some current from the Agilent Power Supply + Unit Under Test, then, the script print these readings as simple as: PS.write(b"MEAS:CURR? \n") time.sleep(2) response = PS.read(1000) time.sleep(3) print(response) (float(response)*1) E3632A=(float(response)*1) print (E3632A) When the script excecute the "print command" (print (E3632A), all the information is displayed into the

问题 I am reading 'UNIX Network Programming: The Sockets Networking API' and in the example code they have an error handling function which contains the following lines: fflush(stdout); /* in case stdout and stderr are the same */ fputs(buf, stderr); fflush(stderr); Where buf contains the error description. I don't understand why fflush is used on stdout on the first line and why the comment explains the reason for its use. 回答1: This is because of buffering. Stdout and stderr are usually buffered

问题 I need to disable sys.stderr messages, which produced by some *.jar file. This *.jar file is calling by subprocess.check_call(cmd) from sklear2pmml method __init__.py of external library ( sklear2pmml library). I know, that I can disable stderr by changing library code to something like this: fnull = open(os.devnull,'w') subprocess.check_call(cmd,stderr=fnull) But this treak leads to changing python library, that I don't want. How can I fix stderr output without this side effect? 回答1: One

问题 I completly don't understand this behaviour. I have a very simple Perl script: #!/usr/bin/perl use strict; use warnings; print "line 1\n"; print STDERR "line 2\n"; If I run it from console I will get what I expect: $ perl a.pl line 1 line 2 But if I redirect it to file, I will get the lines in the reverse order: $ perl a.pl &> a $ cat a line 2 line 1 How can I capture all the outputs STDOUT+STDERR to the file with the same order I get in the console? 回答1: This is an effect of buffering. When

问题 I want to read both stderr and stdout from a child process, but it doesn't work. main.rs use std::process::{Command, Stdio}; use std::io::{BufRead, BufReader}; fn main() { let mut child = Command::new("./1.sh") .stdout(Stdio::piped()) .stderr(Stdio::piped()) .spawn() .unwrap(); let out = BufReader::new(child.stdout.take().unwrap()); let err = BufReader::new(child.stderr.take().unwrap()); out.lines().for_each(|line| println!("out: {}", line.unwrap()) ); err.lines().for_each(|line| println!(

问题 I want to read both stderr and stdout from a child process, but it doesn't work. main.rs use std::process::{Command, Stdio}; use std::io::{BufRead, BufReader}; fn main() { let mut child = Command::new("./1.sh") .stdout(Stdio::piped()) .stderr(Stdio::piped()) .spawn() .unwrap(); let out = BufReader::new(child.stdout.take().unwrap()); let err = BufReader::new(child.stderr.take().unwrap()); out.lines().for_each(|line| println!("out: {}", line.unwrap()) ); err.lines().for_each(|line| println!(

问题 I'm on a Linux Ubuntu 12.04 system. I have been using this code to log all stdout and stderr + additional logging on INFO level to a file.. class LogFile(object): def __init__(self, name=None): self.logger = logging.getLogger(name) def write(self, msg, level=logging.INFO): self.logger.log(level, msg) def flush(self): for handler in self.logger.handlers: handler.flush() logging.basicConfig(level=logging.INFO, format='%(asctime)s %(name)-12s %(levelname)-8s %(message)s', datefmt='%m-%d-%y %H:%M

问题 I am writing a C program where I am printing to stderr and also using putchar() within the code. I want the output on the console to show all of the stderr and then finally flush the stdout before the program ends. Does anyone know of a method that will stop stdout from flushing when a putchar('\n') occurs? I suppose i could just do an if statement to make sure it doesn't putchar any newlines but I would prefer some line or lines of code to put at the top of the program to stop all flushing

问题 I am writing a C program where I am printing to stderr and also using putchar() within the code. I want the output on the console to show all of the stderr and then finally flush the stdout before the program ends. Does anyone know of a method that will stop stdout from flushing when a putchar('\n') occurs? I suppose i could just do an if statement to make sure it doesn't putchar any newlines but I would prefer some line or lines of code to put at the top of the program to stop all flushing