sys::exec_wait("command", "-v", "foo") seems to not work

[philipp-baumann]

Don't know if this is expected behavior, edge case, or my own wrong usage.

> out <- system2("command", "-v", "nix-build")
> sys::exec_wait("command", "-v", "nix-build")
Error: Failed to execute 'command' (No such file or directory)
> out
[1] 0

[jeroen]

sys runs programs, but maybe on your system, command is not an executable, but a shell-built-in:

See: https://www.gnu.org/software/bash/manual/html_node/Bash-Builtins.html

In this case you need to invoke your shell program to use that command, which is what system2 does:

sys::exec_wait("sh", c("-c", "command -v nix-build"))

If you just want to test if a program exists on the path, you can also use:

Sys.which("nix-build")

[philipp-baumann]

thank you so much for explaining!