This will therefore not output anything if both standard output and standard error are redirected to files or devices or anything not a terminal it does not emit ANSI escape codes to redirected output. If n is 3, clear entire screen and delete all lines saved in the scrollback buffer (some terminals only). If n is 1, clear from cursor to beginning of the screen. If n is 0 (or missing), clear from cursor to end of screen. The above commands use POSIX shell redirection to ensure the output of the command goes to the desired descriptor, and that any error messages from the shell or the command (say, if it does not exist) is redirected to the null device, i.e. Defined in index.d.ts:140 Clears part of the screen. Per POSIX.1, system() uses a POSIX shell. To check if standard output or standard error is a terminal, and if one is, use the ncurses clear command-line command to clear it. So, technically, you could use for example if (isatty(1)) For maximum compatibility, you can use the macros STDIN_FILENO, STDOUT_FILENO, and STDERR_FILENO for the three standard file descriptors, although in Linux, they are always 0, 1, and 2, respectively. In Unix and POSIXy systems, you can use the isatty() function to test if a file descriptor refers to a terminal. (If ANSI.SYS was loaded, then the ANSI escape sequence mentioned above would have worked just fine too.) ESC J Clear to end of screen Clear screen from cursor onwards. This executed an MS-DOS command, cls, that cleared the screen. ESC I Cursor up and insert Move cursor one line upwards and scroll. In the MS-DOS era, over two decades ago, the idiom system("cls") was common. For example, if it is just because you find it easier to read the output, just pipe the output through less, or run clear. Not wanting to use the terminal interface but wanting to clear the terminal is an odd combination atypical in the Unix or POSIX environments. You can use either the C library interface, or the command-line utilities ( clear or reset, the latter resetting the terminal properties back to normal/defaults, in case a previous program left them in an odd or unusable state). To use the terminal interface, you use ncurses. So, it is not a good idea to hard-code the sequence, but use the terminal interface. While these sequences work for most (if not all) current terminal emulators, the actual codes generated are from the POSIX terminal interface database for the current terminal. "\033[2J" = CSI 2 J: Clear terminal screen. Im currently filtering/evaluating the ANSI codes in a terminal screen reader Im writing, but Im not sure what these are. "\033[H" = CSI H: Move cursor to top left corner. "\033[3J" = CSI 3 J: Clear terminal screen and delete everything in the scrollback buffer. The actual sequence is "\033[3J\033[H\033[2J", and contains three ANSI escape codes:
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