# Run Julia from Julia

**URL:** <https://discourse.julialang.org/t/run-julia-from-julia/117945>\
**Category:** General Usage\
**Tags:** question\
**Created:** [August 8, 2024, 7:51am UTC](https://discourse.julialang.org/t/run-julia-from-julia/117945 "2024-08-08T07:51:23Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![ufechner7](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ufechner7/32/51363_2.png) [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Post date:** [August 8, 2024, 7:51am UTC](https://discourse.julialang.org/t/run-julia-from-julia/117945/1 "2024-08-08T07:51:23Z")

</div>

It would be comfortable if users could use a few of my packages like this:

```julia
mkdir demo
cd demo
julia --project="."
using Pkg
pkg"add MyPackage"
using MyPackage
install()
compile()

```

Then restart Julia, and then the freshly compiled package image is used and the examples are available.

The install() function would create the folders `data` and `examples` and copy some example input data and some example scripts.

The compile() function would launch a bash script that creates a system image and installs the packages needed to run the examples. The script could be similar to this one:

```julia
update=false
if [[$# -gt 0]]; then
    if [[$1 != "--update"]]; then
        echo "Invalid parameter! Use:"
        echo "./create_sys_image"
        echo "or"
        echo "./create_sys_image --update"
        exit 1
    else
        update=true
    fi
fi

if [[$(basename $(pwd)) == "bin"]]; then
    cd ..
fi

julia_version=$(julia --version | awk '{print($3)}')
julia_major=${julia_version:0:3}
if [[$julia_major == "1.1"]]; then
    julia_major=${julia_version:0:4} 
fi
if [-d .git] || git rev-parse --git-dir > /dev/null 2>&1 ; then
    branch=$(git rev-parse --abbrev-ref HEAD)
else
    branch=""
fi
if test -f "kps-image-${julia_major}-${branch}.so"; then
    mv bin/kps-image-${julia_major}-${branch}.so kps-image-${julia_major}-${branch}.so.bak
fi
julia -e "using Pkg; Pkg.add(\"TestEnv\")"

if [[$update == true]]; then
    echo "Updating packages..."
    if test -f "Manifest.toml"; then
        mv Manifest.toml Manifest.toml.bak
    fi
    julia --pkgimages=no --project -e "include(\"./test/update_packages.jl\");"
else
    if [[$julia_major == "1.9"]]; then
        cp Manifest-1.9.toml.default Manifest.toml
        echo "Using Manifest-1.9.toml.default ..."        
    else
        cp Manifest-1.10.toml.default Manifest.toml
        echo "Using Manifest-1.10.toml.default ..."
    fi
fi
julia --pkgimages=no --project -e "include(\"./test/create_sys_image.jl\");"
if [[$branch != ""]]; then
    SOFILE="bin/kps-image-${julia_major}-${branch}.so"
else
    SOFILE="bin/kps-image-${julia_major}.so"
fi
if test -f $SOFILE; then
    mv $SOFILE $SOFILE.bak
fi
mv kps-image_tmp.so $SOFILE
julia --project -e "using Pkg; Pkg.precompile(); Pkg.resolve()"
if [-d src]; then
    cd src
    touch *.jl # make sure all modules get recompiled in the next step
    cd ..
fi
echo "Precompiling package KiteModels..."
julia --project -J $SOFILE -e "using KiteModels, KitePodModels, KiteUtils"
echo "Precompiling package ControlPlots..."
if [[$branch != ""]]; then
    julia --project -J $SOFILE -e "using TestEnv; TestEnv.activate(); using ControlPlots"
else
    julia --project -J $SOFILE -e "using ControlPlots"
fi

```

Open questions:

- can I launch a new Julia instance from a Julia function?
- can I modify startup.jl such that it automatically uses a system image that is present in a project?

---

<div class="post-metadata">

**Author:** ![carstenbauer](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/carstenbauer/32/4981_2.png) [@carstenbauer](https://discourse.julialang.org/u/carstenbauer)\
**Post date:** [August 8, 2024, 7:58am UTC](https://discourse.julialang.org/t/run-julia-from-julia/117945/2 "2024-08-08T07:58:27Z")

</div>

> [@ufechner7](#):
>
> can I launch a new Julia instance from a Julia function?

Sure, you can use `run` and `Base.julia_cmd()`. See e.g. [ThreadPinning.jl/test/tests\_mpi.jl at main · carstenbauer/ThreadPinning.jl · GitHub](https://github.com/carstenbauer/ThreadPinning.jl/blob/main/test/tests_mpi.jl) for inspiration, where I spawn MPI ranks running Julia (for testing purposes).

(Disclaimer: I didn’t read the entire post.)

---

<div class="post-metadata">

**Author:** ![carstenbauer](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/carstenbauer/32/4981_2.png) [@carstenbauer](https://discourse.julialang.org/u/carstenbauer)\
**Post date:** [August 8, 2024, 8:00am UTC](https://discourse.julialang.org/t/run-julia-from-julia/117945/3 "2024-08-08T08:00:58Z")

</div>

If your goal is to replace the current Julia process by a new one without the user noticing, you can do this as well. But since this is pretty nuts, I won’t describe it here and just link to [the relevant bit](https://github.com/JuliaPerf/ScoreP.jl/blob/ef8ec59aa24466beff538f8a931ce2f2617ecc50/src/utility.jl#L230) of one of my darkest projects.

---

<div class="post-metadata">

**Author:** ![ufechner7](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ufechner7/32/51363_2.png) [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Post date:** [August 8, 2024, 8:03am UTC](https://discourse.julialang.org/t/run-julia-from-julia/117945/4 "2024-08-08T08:03:58Z")

</div>

> [@carstenbauer](#):
>
> But since this is pretty nuts

Why is it `nuts`? Would it be better to add this functionality to the julia starter program provided by juliaup, written in Rust?

I mean, automatically using a system image with a pre-defined name that is present in the current project folder seams like a pretty standard feature which could be useful in many scenarios.

---

<div class="post-metadata">

**Author:** ![tecosaur](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tecosaur/32/23206_2.png) [@tecosaur](https://discourse.julialang.org/u/tecosaur)\
**Post date:** [August 8, 2024, 8:37am UTC](https://discourse.julialang.org/t/run-julia-from-julia/117945/5 "2024-08-08T08:37:17Z")

</div>

I do something a bit like this in the docs building of a package of mine.

> <https://github.com/tecosaur/DataToolkit.jl/blob/main/Core/docs/setup.jl#L12-L36>