title: IRkernel::installspec() error when making kernel available to Jupyter on macOS Catalina
body: <p>I am following the instructions on <a href="https://irkernel.github.io/installation/" rel="nofollow noreferrer">this page</a> to install IRkernel (with hopes of someday using the awesome <a href="https://nteract.gitbooks.io/hydrogen/" rel="nofollow noreferrer">Hydrogen package</a> in Atom) and ran across the following error:</p>
  
  <p>I started by following the directions <a href="https://nteract.io/kernels/r" rel="nofollow noreferrer">here</a>.</p>
  
  <p><em>In the terminal, I entered the following:</em></p>
  
  <pre class="lang-r prettyprint-override"><code>&gt; install.packages(c('repr', 'IRdisplay', 
  &gt; 'evaluate', 'crayon', 'pbdZMQ', 
  &gt; 'devtools', 'uuid', 'digest'))
  </code></pre>
  
  <p><em>These all install just fine because I saw the following:</em></p>
  
  <pre class="lang-r prettyprint-override"><code>The downloaded binary packages are in
  /var/folders/fl/kv1bdvrx04524bnvdzhfx3p80000gn/T//RtmpwpXpvs/downloaded_packages
  </code></pre>
  
  <p>Next I installed the <code>IRkernel</code> package covered both <a href="https://nteract.io/kernels/r" rel="nofollow noreferrer">here</a> and <a href="https://irkernel.github.io/installation/" rel="nofollow noreferrer">here</a>.  </p>
  
  <pre class="lang-r prettyprint-override"><code>devtools::install_github('IRkernel/IRkernel')
  # ... this all installs fine...
  * installing *source* package ‘IRkernel’ ...
  ** using staged installation
  ** R
  ** inst
  ** byte-compile and prepare package for lazy loading
  ** help
  *** installing help indices
  ** building package indices
  ** testing if installed package can be loaded from temporary location
  ** testing if installed package can be loaded from final location
  ** testing if installed package keeps a record of temporary installation path
  * DONE (IRkernel)
  </code></pre>
  
  <p>Then when I try to make the kernel visible to jupyter (step 2/2), I get the following error in the Terminal (running R). </p>
  
  <pre class="lang-r prettyprint-override"><code>&gt; IRkernel::installspec()
  Error in IRkernel::installspec() :
  jupyter-client has to be installed but “jupyter kernelspec --version” exited with code 127.
  In addition: Warning message:
  In system2("jupyter", c("kernelspec", "--version"), FALSE, FALSE) :
  error in running command
  </code></pre>
  
  <p>My operating system information is below. </p>
  
  <pre class="lang-r prettyprint-override"><code>&gt; devtools::session_info()
  
  ─ Session info ───────────────────────────────────────────────────────────────
  setting  value
  version  R version 3.6.1 (2019-07-05)
  os macOS Catalina 10.15.1
  system x86_64, darwin15.6.0
  ui X11
  language (EN)
  collate  en_US.UTF-8
  ctype  en_US.UTF-8
  tz America/Los_Angeles
  date 2019-12-07
  
  
  
  ─ Packages ───────────────────────────────────────────────────────────────────
  package * version date lib source
  assertthat  0.2.1 2019-03-21 [1] CRAN (R 3.6.0)
  backports 1.1.5 2019-10-02 [1] CRAN (R 3.6.0)
  base64enc 0.1-3 2015-07-28 [1] CRAN (R 3.6.0)
  callr 3.3.2 2019-09-22 [1] CRAN (R 3.6.0)
  cli 1.1.0 2019-03-19 [1] CRAN (R 3.6.0)
  crayon  1.3.4 2017-09-16 [1] CRAN (R 3.6.0)
  curl  4.3 2019-12-02 [1] CRAN (R 3.6.1)
  desc  1.2.0 2018-05-01 [1] CRAN (R 3.6.0)
  devtools  2.2.1 2019-09-24 [1] CRAN (R 3.6.0)
  digest  0.6.23  2019-11-23 [1] CRAN (R 3.6.0)
  ellipsis  0.3.0 2019-09-20 [1] CRAN (R 3.6.0)
  evaluate  0.14  2019-05-28 [1] CRAN (R 3.6.0)
  fs  1.3.1 2019-05-06 [1] CRAN (R 3.6.0)
  glue  1.3.1 2019-03-12 [1] CRAN (R 3.6.0)
  htmltools 0.4.0 2019-10-04 [1] CRAN (R 3.6.0)
  IRdisplay 0.7.0 2018-11-29 [1] CRAN (R 3.6.0)
  IRkernel  1.1 2019-12-08 [1] Github (IRkernel/IRkernel@a56a248)
  jsonlite  1.6 2018-12-07 [1] CRAN (R 3.6.0)
  magrittr  1.5 2014-11-22 [1] CRAN (R 3.6.0)
  memoise 1.1.0 2017-04-21 [1] CRAN (R 3.6.0)
  pbdZMQ  0.3-3 2018-05-05 [1] CRAN (R 3.6.0)
  pillar  1.4.2 2019-06-29 [1] CRAN (R 3.6.0)
  pkgbuild  1.0.6 2019-10-09 [1] CRAN (R 3.6.0)
  pkgload 1.0.2 2018-10-29 [1] CRAN (R 3.6.0)
  prettyunits 1.0.2 2015-07-13 [1] CRAN (R 3.6.0)
  processx  3.4.1 2019-07-18 [1] CRAN (R 3.6.0)
  ps  1.3.0 2018-12-21 [1] CRAN (R 3.6.0)
  R6  2.4.1 2019-11-12 [1] CRAN (R 3.6.0)
  Rcpp  1.0.3 2019-11-08 [1] CRAN (R 3.6.1)
  remotes 2.1.0 2019-06-24 [1] CRAN (R 3.6.0)
  repr  1.0.1 2019-05-14 [1] CRAN (R 3.6.0)
  rlang 0.4.2 2019-11-23 [1] CRAN (R 3.6.0)
  rprojroot 1.3-2 2018-01-03 [1] CRAN (R 3.6.0)
  sessioninfo 1.1.1 2018-11-05 [1] CRAN (R 3.6.0)
  testthat  2.3.1 2019-12-01 [1] CRAN (R 3.6.1)
  usethis 1.5.1 2019-07-04 [1] CRAN (R 3.6.0)
  uuid  0.1-2 2015-07-28 [1] CRAN (R 3.6.0)
  withr 2.1.2 2018-03-15 [1] CRAN (R 3.6.0)
  [1] /Library/Frameworks/R.framework/Versions/3.6/Resources/library
  </code></pre>
  
  <p>Thank you in advance for your time!</p>