stderr

My program calls library functions which print to stderr. I want to intervene so that all write calls to file descriptor #2 will instead get sent to somewhere else. Here is my first attempt: bool redirect_stderr (int fd) { return dup2 (2, fd) > 0; } Here, fd was successfully obtained from open("/foo/bar",O_APPEND|O_CREAT) After this function returns true, std::cerr<<"blah" goes to the terminal and not to the file. What am I doing wrong? Thanks. UPDATE Thanks, larsmans, but I'm not there yet... void redirect_stderr_to (const char * output_file) { int fd = open (output_file, O_APPEND | O_CREAT,

I am going to execute a Process (lame.exe) to encode a WAV file to MP3. I want to process the STDOUT and STDERR of the process to display progress information. Do I need to use threading? I can't get my head around it. Some simple example code would be appreciated. Thanks If running via the Process class, you can redirect the streams so you may process them. You can read from stdout or stderr synchronously or asynchronously. To enable redirecting, set the appropriate redirection properties to true for the streams you want to redirect (e.g., RedirectStandardOutput ) and set UseShellExecute to

模拟ssh远程执行命令 一、服务器 from socket import * import subprocess server = socket(AF_INET, SOCK_STREAM) server.bind(('127.0.0.1', 8000)) server.listen(5) print('start...') while True: conn, client_addr = server.accept() while True: print('from client:', client_addr) cmd = conn.recv(1024) if len(cmd) == 0: break print('cmd:', cmd) obj = subprocess.Popen(cmd.decode('utf8'), # 输入的cmd命令 shell=True, # 通过shell运行 stderr=subprocess.PIPE, # 把错误输出放入管道，以便打印 stdout=subprocess.PIPE) # 把正确输出放入管道，以便打印 # 执行正确的结果，b格式, gbk编码（windows平台） # stdout是二进制 stdout = obj.stdout.read() # 打印正确输出 stderr = obj.stderr.read() # 打印错误输出

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say I'm running an exe from a python script using: subprocess.call(cmdArgs,stdout=outf, stderr=errf) when outf and errf are file descriptors of text files. is there any way I can generate on top of it a merged and synced text file of both stdout and stderr? it should be formatted with time and source(our/err). thanks It is a bit tricky, since you need to poll the stdout and stderr file descriptors of the subprocess while it's running, to get accurate timestamps. You also need to chop up the output into a list of lines so the final results can be merged and sorted easily. You could easily merge

I've searched the Internet and have found some good solutions for teeing STDOUT to 2 different places. Like to a log file and also to the screen at the same time. Here's one example: use IO::Tee; my $log_filename = "log.txt"; my $log_filehandle; open( $log_filehandle, '>>', $log_filename ) or die("Can't open $log_filename for append: $!"); my $tee = IO::Tee->new( $log_filehandle, \*STDOUT ); select $tee; But this solution leaves STDERR going only to the screen and I want STDERR go to both the screen and also to the same log file that STDOUT is being logged to. Is that even possible? My task is