When I installed rkhunter by dnf, and tested, then it always reporting warnings described in actual results.

Reproducible: Always

Steps to Reproduce:
1.# rkhunter --update --propupd
Actual Results:  
grep: warning: stray \ before -
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
grep: warning: stray \ before +
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
[ Rootkit Hunter version 1.4.6 ]
File updated: searched for 177 files, found 135

Checking rkhunter data files...
egrep: warning: egrep is obsolescent; using grep -E
egrep: warning: egrep is obsolescent; using grep -E
  Checking file mirrors.dat                                  [ No update ]
egrep: warning: egrep is obsolescent; using grep -E
  Checking file programs_bad.dat                             [ No update ]
egrep: warning: egrep is obsolescent; using grep -E
  Checking file backdoorports.dat                            [ No update ]
egrep: warning: egrep is obsolescent; using grep -E
  Checking file suspscan.dat                                 [ No update ]
egrep: warning: egrep is obsolescent; using grep -E
  Checking file i18n/cn                                      [ No update ]
  Checking file i18n/de                                      [ No update ]
  Checking file i18n/en                                      [ No update ]
  Checking file i18n/tr                                      [ No update ]
  Checking file i18n/tr.utf8                                 [ No update ]
  Checking file i18n/zh                                      [ No update ]
  Checking file i18n/zh.utf8                                 [ No update ]
  Checking file i18n/ja                                      [ No update ]

Expected Results:  
[ Rootkit Hunter version 1.4.6 ]
File updated: searched for 177 files, found 135

Checking rkhunter data files...
  Checking file mirrors.dat                                  [ No update ]
  Checking file programs_bad.dat                             [ No update ]
  Checking file backdoorports.dat                            [ No update ]
  Checking file suspscan.dat                                 [ No update ]
  Checking file i18n/cn                                      [ No update ]
  Checking file i18n/de                                      [ No update ]
  Checking file i18n/en                                      [ No update ]
  Checking file i18n/tr                                      [ No update ]
  Checking file i18n/tr.utf8                                 [ No update ]
  Checking file i18n/zh                                      [ No update ]
  Checking file i18n/zh.utf8                                 [ No update ]
  Checking file i18n/ja                                      [ No update ]