absolutely wild that there seems to be no single standard linux program that simply takes a filename as one argument and text to write to it as another, without needing to use shell features like io redirection, pipes or herestrings Oo
Edit: Yes I know I can spawn a shell if I don't have one (e.g. in a systemd service's ExecStartPre etc.), I know plenty of other workarounds I could use too. All I wanted to say is that it's weird that such a workaround is needed.