[bash] try to use bash-completions’s _known_hosts_real() for getting hostnames

If defined, use bash-completions’s `_known_hosts_real()`-function to create the
list of hostnames.
This obviously requires bash-completion to be sourced before fzf.

If not defined, fall back to the previous code.

Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>

shell/completion.bash

@@ -412,10 +412,22 @@ _fzf_proc_completion_post() {
 # desired sorting and with any duplicates removed, to standard output.
 if ! declare -F __fzf_list_hosts > /dev/null; then
   __fzf_list_hosts() {
-    command cat <(command tail -n +1 ~/.ssh/config ~/.ssh/config.d/* /etc/ssh/ssh_config 2> /dev/null | command grep -i '^\s*host\(name\)\? ' | command awk '{for (i = 2; i <= NF; i++) print $1 " " $i}' | command grep -v '[*?%]') \
-      <(command grep -oE '^[[a-z0-9.,:-]+' ~/.ssh/known_hosts 2> /dev/null | command tr ',' '\n' | command tr -d '[' | command awk '{ print $1 " " $1 }') \
-      <(command grep -v '^\s*\(#\|$\)' /etc/hosts 2> /dev/null | command grep -Fv '0.0.0.0') |
-      command awk '{if (length($2) > 0) {print $2}}' | command sort -u
+    if declare -F _known_hosts_real > /dev/null; then
+      # if available, use bash-completions’s _known_hosts_real() for getting the list of hosts
+
+      # set the local attribute for any non-local variable that is set by _known_hosts_real()
+      local COMPREPLY=()
+
+      _known_hosts_real ''
+      printf '%s\n' "${COMPREPLY[@]}" | command sort -u --version-sort
+    else
+      # otherwise, get a list of hosts on our own
+
+      command cat <(command tail -n +1 ~/.ssh/config ~/.ssh/config.d/* /etc/ssh/ssh_config 2> /dev/null | command grep -i '^\s*host\(name\)\? ' | command awk '{for (i = 2; i <= NF; i++) print $1 " " $i}' | command grep -v '[*?%]') \
+        <(command grep -oE '^[[a-z0-9.,:-]+' ~/.ssh/known_hosts 2> /dev/null | command tr ',' '\n' | command tr -d '[' | command awk '{ print $1 " " $1 }') \
+        <(command grep -v '^\s*\(#\|$\)' /etc/hosts 2> /dev/null | command grep -Fv '0.0.0.0') |
+        command awk '{if (length($2) > 0) {print $2}}' | command sort -u
+    fi
   }
 fi