Request: Add an API for configuring julia_cmd

base/sysimg.jl

@@ -470,6 +470,7 @@ function __init__()
     # Base library init
     reinit_stdio()
     Multimedia.reinit_displays() # since Multimedia.displays uses stdout as fallback
+    set_julia_basecmd()
     # initialize loading
     init_depot_path()
     init_load_path()

base/util.jl

@@ -400,7 +400,18 @@ printstyled(io::IO, msg...; bold::Bool=false, color::Union{Int,Symbol}=:normal)
 printstyled(msg...; bold::Bool=false, color::Union{Int,Symbol}=:normal) =
     printstyled(stdout, msg...; bold=bold, color=color)
 
-function julia_cmd(julia=joinpath(Sys.BINDIR::String, julia_exename()))
+"""
+    julia_cmd([julia]) -> Cmd
+
+Return a [`Cmd`](@ref) that can be used to launch a `julia` program
+that inherits the command line options of the current executing
+process.  An optional argument can be passed to specify the `julia`
+program to be used instead of [`julia_basecmd`](@ref).  Note that
+package load path settings are not automatically reflected in the
+launched process.  Use [`Base.load_path_setup_code`](@ref) to
+replicate the load paths.
+"""
+function julia_cmd(julia=julia_basecmd())
     opts = JLOptions()
     cpu_target = unsafe_string(opts.cpu_target)
     image_file = unsafe_string(opts.image_file)
@@ -436,6 +447,33 @@ function julia_exename()
     end
 end
 
+"""
+    default_julia_basecmd() -> Cmd
+
+Default `julia` executable and options.
+"""
+default_julia_basecmd() = `$(joinpath(Sys.BINDIR::String, julia_exename()))`
+
+const _julia_basecmd = Ref(``)
+
+"""
+    julia_basecmd() -> Cmd
+
+Julia executable which is used by [`julia_cmd`](@ref).  It may be
+changed by [`set_julia_basecmd`](@ref).
+"""
+julia_basecmd() = _julia_basecmd[]
+
+"""
+    set_julia_basecmd([path::Cmd])
+
+Set the Julia executable used by [`julia_cmd`](@ref).  Reset to default
+when no argument is given.
+"""
+function set_julia_basecmd(cmd::Cmd = default_julia_basecmd())
+    _julia_basecmd[] = cmd
+end
+
 """
     securezero!(o)
 

stdlib/Distributed/src/Distributed.jl

@@ -11,7 +11,7 @@ import Base: getindex, wait, put!, take!, fetch, isready, push!, length,
 
 # imports for use
 using Base: Process, Semaphore, JLOptions, AnyDict, buffer_writes, wait_connected,
-            VERSION_STRING, binding_module, notify_error, atexit, julia_exename,
+            VERSION_STRING, binding_module, notify_error, atexit, julia_basecmd,
             julia_cmd, AsyncGenerator, acquire, release, invokelatest,
             shell_escape_posixly, uv_error, something, notnothing
 

stdlib/Distributed/src/cluster.jl

@@ -443,7 +443,7 @@ end
 default_addprocs_params() = AnyDict(
     :topology => :all_to_all,
     :dir      => pwd(),
-    :exename  => joinpath(Sys.BINDIR, julia_exename()),
+    :exename  => julia_basecmd(),
     :exeflags => ``,
     :enable_threaded_blas => false,
     :lazy => true)