install.packages("swirl")

------------------------- ANTICONF ERROR -------------------------      --
Configuration failed because libcurl was not found. Try installing:
 * deb: libcurl4-openssl-dev (Debian, Ubuntu, etc)
 * rpm: libcurl-devel (Fedora, CentOS, RHEL)
 * csw: libcurl_dev (Solaris)
If libcurl is already installed, check that 'pkg-config' is in your
PATH and PKG_CONFIG_PATH contains a libcurl.pc file. If pkg-config
is unavailable you can set INCLUDE_DIR and LIB_DIR manually via:
R CMD INSTALL --configure-vars='INCLUDE_DIR=... LIB_DIR=...'
--------------------------------------------------------------------
ERROR: configuration failed for package ‘curl’
* removing ‘/home/franco/R/x86_64-pc-linux-gnu-library/3.1/curl’
Warning in install.packages :
  installation of package ‘curl’ had non-zero exit status
* installing *source* package ‘RCurl’ ...
** package ‘RCurl’ successfully unpacked and MD5 sums checked
checking for curl-config... no
Cannot find curl-config
ERROR: configuration failed for package ‘RCurl’
* removing ‘/home/franco/R/x86_64-pc-linux-gnu-library/3.1/RCurl’
Warning in install.packages :
  installation of package ‘RCurl’ had non-zero exit status
ERROR: dependency ‘curl’ is not available for package ‘httr’
* removing ‘/home/franco/R/x86_64-pc-linux-gnu-library/3.1/httr’
Warning in install.packages :
  installation of package ‘httr’ had non-zero exit status
ERROR: dependencies ‘httr’, ‘RCurl’ are not available for package       ‘swirl’
* removing ‘/home/franco/R/x86_64-pc-linux-gnu-library/3.1/swirl’
Warning in install.packages :
  installation of package ‘swirl’ had non-zero exit status

The downloaded source packages are in
    ‘/tmp/Rtmp7G87EM/downloaded_packages’

sudo apt-get install libcurl4-gnutls-dev