Warn when using deprecated rgrep.

src/ShellCheck/Analytics.hs

@@ -3029,7 +3029,7 @@ checkShouldUseGrepQ params t =
             T_DollarExpansion _ [x] -> getPipeline x
             T_Pipeline _ _ cmds -> return cmds
             _ -> fail "unknown"
-    isGrep = (`elem` ["grep", "egrep", "fgrep", "zgrep"])
+    isGrep = (`elem` ["grep", "egrep", "fgrep", "rgrep", "zgrep"])
 
 prop_checkTestArgumentSplitting1 = verify checkTestArgumentSplitting "[ -e *.mp3 ]"
 prop_checkTestArgumentSplitting2 = verifyNot checkTestArgumentSplitting "[[ $a == *b* ]]"

src/ShellCheck/Checks/Commands.hs

@@ -91,6 +91,7 @@ commandChecks = [
     ,checkDeprecatedTempfile
     ,checkDeprecatedEgrep
     ,checkDeprecatedFgrep
+    ,checkDeprecatedRgrep
     ,checkWhileGetoptsCase
     ,checkCatastrophicRm
     ,checkLetUsage
@@ -988,6 +989,10 @@ prop_checkDeprecatedFgrep = verify checkDeprecatedFgrep "fgrep '*' files"
 checkDeprecatedFgrep = CommandCheck (Basename "fgrep") $
     \t -> info (getId $ getCommandTokenOrThis t) 2197 "fgrep is non-standard and deprecated. Use grep -F instead."
 
+prop_checkDeprecatedRgrep = verify checkDeprecatedRgrep "rgrep '*' dir"
+checkDeprecatedRgrep = CommandCheck (Basename "rgrep") $
+    \t -> info (getId $ getCommandTokenOrThis t) 2324 "rgrep is non-standard and deprecated. Use grep -r instead."
+
 prop_checkWhileGetoptsCase1 = verify checkWhileGetoptsCase "while getopts 'a:b' x; do case $x in a) foo;; esac; done"
 prop_checkWhileGetoptsCase2 = verify checkWhileGetoptsCase "while getopts 'a:' x; do case $x in a) foo;; b) bar;; esac; done"
 prop_checkWhileGetoptsCase3 = verifyNot checkWhileGetoptsCase "while getopts 'a:b' x; do case $x in a) foo;; b) bar;; *) :;esac; done"