title: R and RStudio not detecting installed PostgreSQL (or any other) ODBC drivers
body: <p>I am trying to connect to a PostgreSQL database using the R ODBC drivers in RStudio. For some reason, the drivers are not being detected by R:</p>
  
  <pre><code>$ Rscript -e 'odbc::odbcListDrivers()'
  [1] name      attribute value    
  &lt;0 rows&gt; (or 0-length row.names)
  </code></pre>
  
  <p>Even though as far as I can tell, they are correctly installed (using homebrew):</p>
  
  <pre><code>$ brew list
  freetds     gettext     git     icu4c       libtool     openssl     pcre2       pkg-config  
  postgresql  psqlodbc    readline    sqlite      sqliteodbc  unixodbc
  
  $ odbcinst -j
  unixODBC 2.3.6
  DRIVERS............: /etc/odbcinst.ini
  SYSTEM DATA SOURCES: /etc/odbc.ini
  FILE DATA SOURCES..: /etc/ODBCDataSources
  USER DATA SOURCES..: /Users/barthf/.odbc.ini
  SQLULEN Size.......: 8
  SQLLEN Size........: 8
  SQLSETPOSIROW Size.: 8
  
  $ cat /etc/odbcinst.ini
  [PostgreSQL Driver]
  Driver          = /usr/local/lib/psqlodbcw.so
  
  [SQLite Driver]
  Driver          = /usr/local/lib/libsqlite3odbc.dylib
  
  $ ls /usr/local/lib/ | grep odbc.*so$
  libsqlite3odbc.so
  libtdsodbc.0.so
  libtdsodbc.so
  psqlodbca.so
  psqlodbcw.so
  </code></pre>
  
  <p>I am running on:</p>
  
  <pre><code>R version 3.4.2 (2017-09-28)
  Platform: x86_64-apple-darwin15.6.0 (64-bit)
  Running under: OS X El Capitan 10.11.6
  
  locale:
  [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
  
  attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods   base     
  
  other attached packages:
  [1] DBI_1.0.0  odbc_1.1.6
  
  loaded via a namespace (and not attached):
   [1] Rcpp_0.12.18      dbplyr_1.1.0      compiler_3.4.2    pillar_1.2.3      later_0.7.1       plyr_1.8.4       
   [7] bindr_0.1.1       base64enc_0.1-3   tools_3.4.2       digest_0.6.12     bit_1.1-12        jsonlite_1.5     
  [13] tibble_1.4.2      nlme_3.1-131      lattice_0.20-35   pkgconfig_2.0.2   rlang_0.2.2       psych_1.7.8      
  [19] shiny_1.0.5       rstudioapi_0.7    parallel_3.4.2    RPostgreSQL_0.6-2 yaml_2.1.14       bindrcpp_0.2.2   
  [25] stringr_1.2.0     httr_1.3.1        dplyr_0.7.5       sparklyr_0.8.4    hms_0.4.2         rprojroot_1.2    
  [31] bit64_0.9-7       grid_3.4.2        tidyselect_0.2.4  glue_1.2.0        R6_2.2.2          foreign_0.8-69   
  [37] tidyr_0.7.2       reshape2_1.4.2    purrr_0.2.5       blob_1.1.1        magrittr_1.5      backports_1.1.1  
  [43] promises_1.0.1    htmltools_0.3.6   mnormt_1.5-5      assertthat_0.2.0  mime_0.5          xtable_1.8-2     
  [49] httpuv_1.4.0      stringi_1.1.5     lazyeval_0.2.1    broom_0.4.2    
  </code></pre>
  
  <p>For some reason unknown to me, the <code>RPostgreSQL::PostgreSQL()</code> driver works fine. However I want to use the ODBC driver so I can make use of the RStudio Connections feature. When I try to use RStudio to create a <code>New Connection</code> the dialog window only shows options for connecting to <code>Livy</code> and <code>Spark</code>. </p>
  
  <p>As suggested, here is the attempted connection code:</p>
  
  <p><strong>Using <code>ODBC</code>:</strong></p>
  
  <pre><code>&gt; con &lt;- DBI::dbConnect(odbc::odbc(),
  +                       driver = "PostgreSQL Driver",
  +                       database = "postgres",
  +                       UID    = rstudioapi::askForPassword("Database user"),
  +                       PWD    = rstudioapi::askForPassword("Database password"),
  +                       host = "localhost",
  +                       port = 5432) ## returns error below
  Error: nanodbc/nanodbc.cpp:950: 01000: [unixODBC][Driver Manager]Can't open lib 'PostgreSQL Driver' : file not found 
  </code></pre>
  
  <p><strong>Using <code>RPostgreSQL</code>:</strong></p>
  
  <pre><code>con &lt;- DBI::dbConnect(RPostgreSQL::PostgreSQL(),
  +   dbname = "postgres",
  +   user    = rstudioapi::askForPassword("Database user"),
  +   password    = rstudioapi::askForPassword("Database password"),
  +   host = "localhost",
  +   port = 5432) ## works fine
  </code></pre>
  
  <p>Any thoughts why the R ODBC drivers do not seem to work? Any suggestions on things that I can try here?</p>