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alcove

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Control plane for Unix processes, containers and sandboxes

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alcove edoc fexecve-5.edoc
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edoc/fexecve-5.edoc 

@doc fexecve(2): replace the process image



Replace the process image, specifying the environment for the new process

image, using a previously opened file descriptor.  The file descriptor

can be set to close after exec() by passing the O_CLOEXEC flag to open:



```

{ok, Pid} = alcove:fork(Drv, []),

{ok, FD} = alcove:open(Drv, [Pid], "/bin/ls", [o_rdonly,o_cloexec], 0),

ok = alcove:fexecve(Drv, [Pid], FD, ["ls", "-al"], ["FOO=123"]).

'''



Linux requires an environment to be set unlike with execve(2). The

environment can be empty:



```

% Environment required on Linux

ok = alcove:fexecve(Drv, [Pid], FD, ["ls", "-al"], [""]).

'''



== Support ==



• Linux



• FreeBSD



== Examples ==



```

1> {ok, Drv} = alcove_drv:start([{exec, "sudo -n"}]).

{ok,<0.177.0>}

2> {ok, Pid} = alcove:fork(Drv, []).

{ok,31491}

3> {ok, FD} = alcove:open(Drv, [Pid], "/usr/bin/env", [o_rdonly,o_cloexec], 0).

{ok,6}

4> alcove:fexecve(Drv, [Pid], FD, ["env", "-0"], ["FOO=123"]).

ok

5> flush().

Shell got {alcove_stdout,<0.177.0>,[31491],<<70,79,79,61,49,50,51,0>>}

Shell got {alcove_event,<0.177.0>,[31491],{exit_status,0}}

ok

'''