# Look up UUID of package by name in the General registry
**URL:** https://discourse.julialang.org/t/look-up-uuid-of-package-by-name-in-the-general-registry/52369
**Category:** General Usage
**Tags:** question
**Created:** [December 25, 2020, 11:55am UTC](https://discourse.julialang.org/t/look-up-uuid-of-package-by-name-in-the-general-registry/52369 "2020-12-25T11:55:16Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)
#### Post date: [December 25, 2020, 11:55am UTC](https://discourse.julialang.org/t/look-up-uuid-of-package-by-name-in-the-general-registry/52369/1 "2020-12-25T11:55:16Z")
How can I look up UUID of a package by name in the General registry (or return `nothing` if there is no such package?)
---
### Author:  [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)
#### Post date: [December 25, 2020, 1:45pm UTC](https://discourse.julialang.org/t/look-up-uuid-of-package-by-name-in-the-general-registry/52369/2 "2020-12-25T13:45:48Z")
```julia
julia> import TOML
julia> function lookup(name)
# Look up Registry.toml files in depots
tomlfiles = String[]
for d in DEPOT_PATH
regs = joinpath(d, "registries")
if isdir(regs)
for r in readdir(regs)
toml = joinpath(regs, r, "Registry.toml")
if isfile(toml)
push!(tomlfiles, toml)
end
end
end
end
# Look up uuids in toml files
uuids = Base.UUID[]
for f in tomlfiles
toml = TOML.parsefile(f)
if haskey(toml, "packages")
for (k, v) in toml["packages"]
if v["name"] == name
push!(uuids, Base.UUID(k))
end
end
end
end
return uuids
end
lookup (generic function with 1 method)
julia> lookup("Literate")
1-element Vector{Base.UUID}:
UUID("98b081ad-f1c9-55d3-8b20-4c87d4299306")
```
---
### Author:  [@Skoffer](https://discourse.julialang.org/u/Skoffer)
#### Post date: [December 25, 2020, 1:52pm UTC](https://discourse.julialang.org/t/look-up-uuid-of-package-by-name-in-the-general-registry/52369/3 "2020-12-25T13:52:27Z")
I think the question was opposite, how to do something like this:
```julia
julia> lookup("Literate")
"98b081ad-f1c9-55d3-8b20-4c87d4299306"
```
---
### Author:  [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)
#### Post date: [December 25, 2020, 2:04pm UTC](https://discourse.julialang.org/t/look-up-uuid-of-package-by-name-in-the-general-registry/52369/4 "2020-12-25T14:04:14Z")
Of course, I inverted the condition somehow. Fixed now.
---
### Author:  [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)
#### Post date: [December 25, 2020, 4:11pm UTC](https://discourse.julialang.org/t/look-up-uuid-of-package-by-name-in-the-general-registry/52369/5 "2020-12-25T16:11:02Z")
Thanks for the nice solution.
Incidentally, I may need to adjust my thinking a bit. I was somehow implicitly assuming that this data is stored in a data structure handled by `Pkg`, which consequently may/should provide an API to extract it.
But in fact, this data is in a TOML file, and when I ask Pkg to do something similar, it parses the same TOML file — I can access this data directly. I have to admit that this did not occur to me.
Incidentally, is the registry TOML format documented somewhere? It is pretty self-explanatory, just being curious.
---
### Author:  [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)
#### Post date: [December 25, 2020, 10:08pm UTC](https://discourse.julialang.org/t/look-up-uuid-of-package-by-name-in-the-general-registry/52369/6 "2020-12-25T22:08:42Z")
On Pkg master (might not be on Julia master) you can do:
```julia
julia> reg = Pkg.Registry.RegistryInstance(joinpath(homedir(), ".julia/registries/General"))
Registry: "General" at "/Users/kristoffercarlsson/.julia/registries/General":
uuid: 23338594-aafe-5451-b93e-139f81909106
repo: https://github.com/JuliaRegistries/General.git
git-tree-sha1: c3b2b9b7518793da48dd6cf56a9337be3dd5195f
packages: 4754
julia> Pkg.Registry.uuids_from_name(reg, "Literate")
1-element Vector{Base.UUID}:
UUID("98b081ad-f1c9-55d3-8b20-4c87d4299306")
```
(of course, these are internal functions).