extSoftVersion()zlib in use.bzlib (from bzip2) in use.liblzma (from xz) in use.PCRE in use.ICU in use (if any, otherwise "").libtre in use.iconv
  library in use (if known).readline in use (if any,
  otherwise "").bzlib and pcre normally contain
  a date as well as the version number, and that for tre includes
  several items separated by spaces, the version number being the
  second. For iconv this will give the implementation as well as the
  version, for example "GNU libiconv 1.14", "glibc
  2.18" or "win_iconv" (which has no version number).libcurlVersion for the version of libCurl. La_version for the version of LAPACK in use. grSoftVersion for third-party graphics software. tclVersion for the version of Tcl/Tk. pcre_config for PCRE configuration options.extSoftVersion()
## the PCRE version
sub(" .*", "", extSoftVersion()["PCRE"])
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