Avoid some unnecessary command invocations.

completions/perl

@@ -121,7 +121,7 @@ _perldoc()
             COMPREPLY=( "${COMPREPLY[@]}" $( compgen -W \
                 '$( PAGER=/bin/cat man perl |  \
                 sed -ne "/perl.*Perl overview/,/perlwin32/p" | \
-                awk "\$NF=2 { print \$1}" | command grep perl )' -- "$cur" ) )
+                awk "\$NF=2 && \$1 ~ /^perl/ { print \$1 }" )' -- "$cur" ) )
         fi
         _filedir 'p@(l|m|od)'
     fi

completions/rpcdebug

@@ -13,9 +13,8 @@ _rpcdebug_flags()
     done
 
     if [ -n "$module" ]; then
-        COMPREPLY=( $( compgen -W "$(rpcdebug -vh 2>&1 \
-            | command grep '^'$module' '\
-            | awk '{$1 = ""; print $0}')" -- "$cur" ) )
+        COMPREPLY=( $( compgen -W "$( rpcdebug -vh 2>&1 | \
+            sed -ne 's/^'$module'[[:space:]]\{1,\}//p' )" -- "$cur" ) )
     fi
 }