stdin

What are the possible ways for reading user input using read() system call in Unix. How can we read from stdin byte by byte using read() ? You can do something like this to read 10 bytes: char buffer[10]; read(STDIN_FILENO, buffer, 10); remember read() doesn't add '\0' to terminate to make it string (just gives raw buffer). To read 1 byte at a time: char ch; while(read(STDIN_FILENO, &ch, 1) > 0) { //do stuff } and don't forget to #include <unistd.h> , STDIN_FILENO defined as macro in this file. There are three standard POSIX file descriptors, corresponding to the three standard streams, which

I am getting "Bus Error" trying to read stdin into a char* variable. I just want to read whole stuff coming over stdin and put it first into a variable, then continue working on the variable. My Code is as follows: char* content; char* c; while( scanf( "%c", c)) { strcat( content, c); } fprintf( stdout, "Size: %d", strlen( content)); But somehow I always get "Bus error" returned by calling cat test.txt | myapp , where myapp is the compiled code above. My question is how do i read stdin until EOF into a variable? As you see in the code, I just want to print the size of input coming over stdin,

Is it possible to synchronously read from stdin in node.js? Because I'm writing a brainfuck to JavaScript compiler in JavaScript (just for fun). Brainfuck supports a read operation which needs to be implemented synchronously. I tried this: const fs = require('fs'); var c = fs.readSync(0,1,null,'utf-8'); console.log('character: '+c+' ('+c.charCodeAt(0)+')'); But this only produces this output: fs:189 var r = binding.read(fd, buffer, offset, length, position); ^ Error: EAGAIN, Resource temporarily unavailable at Object.readSync (fs:189:19) at Object.<anonymous> (/home/.../stdin.js:3:12) at

I'm writing a shell script that should be somewhat secure i.e. does not pass secure data through parameters of commands and preferably does not use temporary files. How can I pass a variable to the stdin of a command? Or, if it's not possible, how to correctly use temporary files for such task? Something as simple as: echo "$blah" | my_cmd Passing a value on stdin is as simple as: your-command <<< "$your_variable" Always make sure you put quotes around variable expressions! Note that the ' echo "$var" | command operations mean that standard input is limited to the line(s) echoed. If you also

I am reading bunch of integers separated by space or newlines from the standard in using Scanner(System.in) . Is there any faster way of doing this in Java? Is there any faster way of doing this in Java? Yes. Scanner is fairly slow (at least according to my experience). If you don't need to validate the input, I suggest you just wrap the stream in a BufferedInputStream and use something like String.split / Integer.parseInt . A small comparison: Reading 17 megabytes (4233600 numbers) using this code Scanner scanner = new Scanner(System.in); while (scanner.hasNext()) sum += scanner.nextInt();

I basically want to test if stdin has input (like if you echo and pipe it). I have found solutions that work, but they are ugly, and I like my solutions to be clean. On linux I use this: bool StdinOpen() { FILE* handle = popen("test -p /dev/stdin", "r"); return pclose(handle) == 0; } I know that I should add more error handling, but it's besides the point. On windows I use this: bool StdinOpen() { static HANDLE handle = GetStdHandle(STD_INPUT_HANDLE); DWORD bytes_left; PeekNamedPipe(handle, NULL, 0, NULL, &bytes_left, NULL); return bytes_left; } That is fine for linux, but I want to know what