Delete [dev] behind pip install -e .
I might be wrong here, but I think it should simply be 
```bash
$ pip install -e .
``` 
without the [dev] 
When executing 
```bash
$ pip install -e .[dev]
``` 
in my terminal I get the error: 
`no matches found: .[dev]`
# [Codecov](https://codecov.io/gh/huggingface/transformers/pull/2316?src=pr&el=h1) Report
> Merging [#2316](https://codecov.io/gh/huggingface/transformers/pull/2316?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/aeef4823ab6099249679756182700e6800024c36?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/2316/graphs/tree.svg?width=650&token=9qOlN6Hb1c&height=150&src=pr)](https://codecov.io/gh/huggingface/transformers/pull/2316?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master    #2316   +/-   ##
=======================================
  Coverage   73.49%   73.49%           
=======================================
  Files          87       87           
  Lines       14793    14793           
=======================================
  Hits        10872    10872           
  Misses       3921     3921
```



------

[Continue to review full report at Codecov](https://codecov.io/gh/huggingface/transformers/pull/2316?src=pr&el=continue).
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<|||||>`[dev]` is there to install the development dependencies.

What shell are you using?

Does `pip install -e ".[dev]"` or `pip install -e .\[dev\]` work?



<|||||>We're probably going to modify the syntax for shell scripts. When we do this, we should modify it throughout the repository, because there are a bunch of other instances of this.<|||||>I see!
I was using the zsh shell. 
`pip install -e ".[dev]"` and `pip install -e .\[dev\]` both work with zsh shell.

When switching to the bash shell 
`pip install -e .[dev]` works as well.<|||||>I'm using zsh as well, but I must have enabled an option that makes the unquoted syntax work.

I'm going to fix the instructions to prevent others from hitting the same problem.<|||||>Thanks for the report!