# Syntax: invalid operator "--"

**URL:** <https://discourse.julialang.org/t/syntax-invalid-operator/63369>\
**Category:** General Usage\
**Tags:** question\
**Created:** [June 22, 2021, 1:55pm UTC](https://discourse.julialang.org/t/syntax-invalid-operator/63369 "2021-06-22T13:55:04Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Amro](https://avatars.discourse-cdn.com/v4/letter/a/4491bb/32.png) [@Amro](https://discourse.julialang.org/u/Amro)\
**Post date:** [June 22, 2021, 1:55pm UTC](https://discourse.julialang.org/t/syntax-invalid-operator/63369/1 "2021-06-22T13:55:04Z")

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## Hello, I am trying to use the command “–threads” in Julia but I got the below error. Any idea for let it run? Thanks

julia\> --threads 4  
ERROR: syntax: invalid operator “–”  
Stacktrace:  
[1] top-level scope  
@ none:1

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**Author:** ![tbeason](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tbeason/32/15898_2.png) [@tbeason](https://discourse.julialang.org/u/tbeason)\
**Post date:** [June 22, 2021, 2:08pm UTC](https://discourse.julialang.org/t/syntax-invalid-operator/63369/2 "2021-06-22T14:08:04Z")

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That is a command line argument that you use when you are starting Julia, eg at the command line you type

```julia
julia --threads 4

```

You cannot change the number of threads after Julia has been started.

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<div class="post-metadata">

**Author:** ![Amro](https://avatars.discourse-cdn.com/v4/letter/a/4491bb/32.png) [@Amro](https://discourse.julialang.org/u/Amro)\
**Post date:** [June 22, 2021, 2:10pm UTC](https://discourse.julialang.org/t/syntax-invalid-operator/63369/3 "2021-06-22T14:10:12Z")

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Thank you very much tbeason! I got it and yes it works