# `Git.Runner.SystemCmd`
[🔗](https://github.com/joshrotenberg/git_wrapper_ex/blob/main/lib/git/runner/system_cmd.ex#L1)

Fallback runner backed by `System.cmd/3`.

Used when the optional `:forcola` dependency is unavailable or on non-POSIX
platforms. Runs git under a `Task` and bounds it with `Task.yield/2` plus
`Task.shutdown/1`. This is the historical behavior of this library and needs
no extra dependencies.

On timeout it returns `{:error, :timeout}`, but be aware that
`Task.shutdown/1` only closes the Erlang port: it does not signal the git OS
process or anything git spawned, so those may keep running after the timeout.
Use `Git.Runner.Forcola` for group-kill semantics.

## Stdin is not supported

`System.cmd/3` cannot write to a child's stdin, and a plain Erlang port
(`Port.open({:spawn_executable, _}, _)`) has no way to half-close stdin: the
child never sees EOF while its stdout pipe stays open, so a command that
reads stdin to EOF before producing output (`hash-object --stdin`, `mktree`,
`stripspace`, `patch-id`, `cat-file --batch`) deadlocks. Rather than ship a
broken stdin path, this runner returns `{:error, :stdin_unsupported}` when
the runner opts carry `:input`. Feeding stdin requires the forcola runner
(`Git.Config.new(runner: :forcola)`), which drives git's stdin over its shim
wire protocol.

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*Consult [api-reference.md](api-reference.md) for complete listing*