This approach creates an odd mini language, which is incomplete: comptime assert(std.mem.indexOfScalar(u8, cmd, '\'') == null); // Quoting isn't supported

This approach creates an odd mini language, which is incomplete: comptime assert(std.mem.indexOfScalar(u8, cmd, '\'') == null); // Quoting isn't supported yet. comptime assert(std.mem.indexOfScalar(u8, cmd, '"') == null); But you can do correct interpolation with simple shell variables, rather than generating shell code strings: $ today='foo; bar' sh -c 'argv git switch --create "release-$today" origin/main' ['git', 'switch', '--create', 'release-foo; bar', 'origin/main'] So that is a test that we can use a plain shell string, without any shell injection bug. (argv is my command to test quoting: python -c 'import sys; print(sys.argv)' "$@" ) Note that there's no escaping function needed, because we're not generating any shell code. We're generating an argv array for `/bin/sh` instead. --- So by invoking with an env var, you can easily create a correct API that uses plain shell git switch --create "release-$today" rather than git switch --create release-{today} # what language is this? It's not obvious If you don't want to use the env var, you can also use git switch --create "release-$1" And invoke with ['sh', '-c', shell_string, 'unused-arg0', today_string] With this approach, you don't need 1. any kind of shell escaping 2. any analyzing of pseudo-shell strings, which can't contain quotes Because you are not generating any shell code. The shell code is constant.