# `GeoGenius.Commands.System`
[🔗](https://github.com/agoodway/geo_genius/blob/main/lib/geo_genius/commands/system.ex#L1)

Runs external executables via `System.cmd/3`.

`available?/2` reports whether the executable can be found on the search
path; its options are ignored, since nothing about a search-path probe
depends on them. `run/3` always merges stdout and stderr into one stream -- a caller
cannot opt out by passing `stderr_to_stdout: false`, because the behaviour
promises one interleaved output and a host that wants the streams kept
apart supplies its own `GeoGenius.Command` instead.

`run/3` never raises. `System.cmd/3` raises `ErlangError` when the
executable cannot be found or cannot be executed at all -- the process
never starts, so there is no `{output, status}` pair to report. This
rescues that and reports the shell's own conventions for the two cases
that matter to a pipeline: 127 for "command not found" (`:enoent`) and 126
for "found but not executable" (`:eacces`). A working directory that does
not exist is checked before `System.cmd/3` runs at all, because the OS
failure that would otherwise produce is a bare non-zero status with no
output naming what went missing.

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