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Sometimes we put some debug prints in our code this way printf("successfully reached at debug-point 1\n"); some code is here printf("successfully reached at debug-point 2"); After the last printf a segmentation fault occurs. Now in this condition only debug-point1 will be print on stdio debug-point 2 print was written to stdio buffer but its not flushed because it didn't get \n so we thinks that crash occur after debug-point1. To over come from this, if I disable buffering option with stdio and stderr stream like this way setvbuf(stdout, NULL, _IONBF, 0); setvbuf(stderr, NULL, _IONBF, 0); Then

How can I define 'catchOutput' so that running main outputs only 'bar'? That is, how can I access both the output stream (stdout) and the actual output of an io action separately? catchOutput :: IO a -> IO (a,String) catchOutput = undefined doSomethingWithOutput :: IO a -> IO () doSomethingWithOutput io = do (_ioOutp, stdOutp) <- catchOutput io if stdOutp == "foo" then putStrLn "bar" else putStrLn "fail!" main = doSomethingWithOutput (putStr "foo") The best hypothetical "solution" I've found so far includes diverting stdout, inspired by this , to a file stream and then reading from that file (

I was wondering how to redirect stderr to multiple outputs. I tried it with this script, but I couldn't get it to work quite right. The first file should have both stdout and stderr, and the 2nd should just have errors. perl script.pl &> errorTestnormal.out &2> errorTest.out Is there a better way to do this? Any help would be much appreciated. Thank you. perl script.pl 2>&1 >errorTestnormal.out | tee -a errorTestnormal.out > errorTest.out Will do what you want. This is a bit messy, lets go through it step by step. We say what used to go to STDERR will now go STDOUT We say what used to go to

I know ffmpeg is able to read data from stdin rather than reading from disk using ffmpeg -i - . Is this supported for all file formats? If it is not, is there a list which file formats are supported? Serge You need to run ffmpeg -protocols to determine if the pipe protocol (the read and write from stdin and stdout) supported in your version of ffmpeg and then ffmpeg -formats to see the list of supported formats. In the excerpt below you will see the note on output pipe that it must be seekable for some protocols. For input protocols it has no such restriction. From man ffmpeg-protocols :

I am trying to write a cat clone to exercise C, I have this code: #include <stdio.h> #define BLOCK_SIZE 512 int main(int argc, const char *argv[]) { if (argc == 1) { // copy stdin to stdout char buffer[BLOCK_SIZE]; while(!feof(stdin)) { size_t bytes = fread(buffer, BLOCK_SIZE, sizeof(char),stdin); fwrite(buffer, bytes, sizeof(char),stdout); } } else printf("Not implemented.\n"); return 0; } I tried echo "1..2..3.." | ./cat and ./cat < garbage.txt but I don't see any output on terminal. What I am doing wrong here? Edit: According to comments and answers, I ended up doing this: void copy

When combining stderr with stdout, why does 2>&1 need to come before a | (pipe) but after a > myfile (redirect to file)? To redirect stderr to stdout for file output: echo > myfile 2>&1 To redirect stderr to stdout for a pipe: echo 2>&1 | less My assumption was that I could just do: echo | less 2>&1 and it would work, but it doesn't. Why not? A pipeline is a |-delimited list of commands . Any redirections you specify apply to the constituent commands (simple or compound), but not to the pipeline as a whole. Each pipe chains one command's stdout to the stdin of the next by implicitly applying a