# JULIA\_DEBUG environment variable
**URL:** https://discourse.julialang.org/t/julia-debug-environment-variable/73278
**Category:** General Usage
**Tags:** question, debug
**Created:** [December 17, 2021, 6:05pm UTC](https://discourse.julialang.org/t/julia-debug-environment-variable/73278 "2021-12-17T18:05:04Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@e3c6](https://discourse.julialang.org/u/e3c6)
#### Post date: [December 17, 2021, 6:05pm UTC](https://discourse.julialang.org/t/julia-debug-environment-variable/73278/1 "2021-12-17T18:05:05Z")
I don’t understand how `JULIA_DEBUG` environment variable works.
```julia
module A
foo() = @debug "foo"
end
A.foo() # nothing printed
ENV["JULIA_DEBUG"] = Main.A
A.foo() # nothing printed
```
Why nothing is printed there?
However if I do:
```julia
ENV["JULIA_DEBUG"] = Main
A.foo()
```
Then there is the debug message printed.
---
### Author:  [@oheil](https://discourse.julialang.org/u/oheil)
#### Post date: [December 19, 2021, 11:10am UTC](https://discourse.julialang.org/t/julia-debug-environment-variable/73278/2 "2021-12-19T11:10:40Z")
It seems that the documentation
[https://docs.julialang.org/en/v1.7/stdlib/Logging/#Environment-variables](https://docs.julialang.org/en/v1.7/stdlib/Logging/#Environment-variables)
is not clear enough or perhaps a bit wrong.
You may open an issue.
I think the proper way of setting ENV[“JULIA\_DEBUG”] are perhaps string values, but I am not sure here and didn’t dive into code:
```julia
julia> module A
foo() = @debug "foo"
end
Main.A
julia> A.foo()
julia> @debug "foo"
julia> ENV["JULIA_DEBUG"] = "A"
"A"
julia> A.foo()
┌ Debug: foo
└ @ Main.A REPL[1]:2
julia> @debug "foo"
julia> ENV["JULIA_DEBUG"] = "Main"
"Main"
julia> A.foo()
┌ Debug: foo
└ @ Main.A REPL[1]:2
julia> @debug "foo"
┌ Debug: foo
└ @ Main REPL[19]:1
```
That `ENV["JULIA_DEBUG"] = "Main"` switches debug on for `Main.A` too, seems also something to argue about.
---
### Author:  [@oheil](https://discourse.julialang.org/u/oheil)
#### Post date: [December 19, 2021, 11:26am UTC](https://discourse.julialang.org/t/julia-debug-environment-variable/73278/3 "2021-12-19T11:26:25Z")
Setting the environment variable with the module, it automatically sets it as String:
```julia
julia> ENV["JULIA_DEBUG"]=Main
Main
julia> typeof(ENV["JULIA_DEBUG"])
String
```
Therefore
```julia
julia> ENV["JULIA_DEBUG"]=A
Main.A
```
is not the same as
```julia
julia> ENV["JULIA_DEBUG"]="A"
A
```
and only the later works for the module A.
This all is an issue in my opinion, which should be opened.
Or you can add to this discussions:
[https://github.com/JuliaLang/julia/issues/28930](https://github.com/JuliaLang/julia/issues/28930)
[https://github.com/JuliaLang/julia/issues/42903](https://github.com/JuliaLang/julia/issues/42903)
---
### Author:  [@Jake](https://discourse.julialang.org/u/Jake)
#### Post date: [April 18, 2022, 9:49pm UTC](https://discourse.julialang.org/t/julia-debug-environment-variable/73278/4 "2022-04-18T21:49:52Z")
According to the document “julia-1.7.2.pdf” page 1147 I should be able to set the environment variable on startup but I get an error as shown.
```julia
Microsoft Windows [Version 10.0.19044.1645]
(c) Microsoft Corporation. All rights reserved.
C:\Users\MyPC>JULIA_DEBUG=loading julia -e 'using DSP'
'JULIA_DEBUG' is not recognized as an internal or external command,
operable program or batch file.
C:\Users\MyPC>
```
However starting julia and executing the following commands seems to work
```julia
julia> using DSP
julia> ENV["JULIA_DEBUG"] = DSP
DSP
```
Is this a windows anomaly or a documentation error?
---
### Author:  [@Sukera](https://discourse.julialang.org/u/Sukera)
#### Post date: [April 18, 2022, 9:57pm UTC](https://discourse.julialang.org/t/julia-debug-environment-variable/73278/5 "2022-04-18T21:57:35Z")
> [@Jake](#):
>
> Is this a windows anomaly or a documentation error?
That’s a windows thing - in `cmd`, you’d use `set JULIA_DEBUG="value"` or in `powershell` you’d do `$env:JULIA_DEBUG="value"`.
Can you link where in the online manual ([docs.julialang.org](http://docs.julialang.org)) that suggestion is? Probably worth a small doc PR, to amend the case for windows.
---
### Author:  [@Jake](https://discourse.julialang.org/u/Jake)
#### Post date: [April 19, 2022, 3:05pm UTC](https://discourse.julialang.org/t/julia-debug-environment-variable/73278/6 "2022-04-19T15:05:30Z")
In the manual julia-1.7.2.pdf it is section 76.4.
This is found online at [Logging · The Julia Language](https://docs.julialang.org/en/v1/stdlib/Logging/) under Environment Variables with a copy shown below:
```julia
$ JULIA_DEBUG=loading julia -e 'using OhMyREPL'
┌ Debug: Rejecting cache file /home/user/.julia/compiled/v0.7/OhMyREPL.ji due to it containing an invalid cache header
└ @ Base loading.jl:1328
[ Info: Recompiling stale cache file /home/user/.julia/compiled/v0.7/OhMyREPL.ji for module OhMyREPL
┌ Debug: Rejecting cache file /home/user/.julia/compiled/v0.7/Tokenize.ji due to it containing an invalid cache header
└ @ Base loading.jl:1328
...
```
Since it is shell (terminal) specific a note that the julia solution is universal may be helpful.
```julia
ENV["JULIA_DEBUG"] = Main
```