tmux: Fix session chooser without fzf

If no fzf is installed, session chooser will now be the old manual
session name input. `tm session-name` will attach or create a session of
the same name, whether fzf is installed or not.

If invoked without argument, and fzf is installed will show a list of
sessions to choose from. If fzf is missing, will create new session
based on current directory.

`tl` has been changed to display the old non-interactive list if no fzf
exists. If fzf has been found however, it points to `tm` instead, since
invoking it without arguments fulfills the same function.

tmux/.config/sh/alias.d/tmux.sh

@@ -6,27 +6,31 @@ exist() { type "$1" >/dev/null 2>&1; }
 # shellcheck disable=2139
 alias tmux="tmux -f ${XDG_CONFIG_HOME:-$HOME/.config}/tmux/tmux.conf"
 
-# show a list of running tmux sessions
-alias tl='tmux list-sessions -F "#{session_name}" 2>/dev/null'
-
 # fzf
 if exist fzf; then
   # fzf select a tmux session to connect to, with pane preview
-  alias tm='fzf_tmux_session'
+  alias tm='_fzf_tmux_attach_start_session'
+  alias tl=tm
+else
+  alias tm='tmux_attach_start'
+  # show a list of running tmux sessions
+  alias tl='tmux list-sessions -F "#{session_name}" 2>/dev/null '
 fi
 
-fzf_tmux_session() {
+_fzf_tmux_list_sessions() {
+  tmux list-sessions -F "#{session_name}" 2>/dev/null | fzf \
+    --layout=reverse \
+    --height=50% \
+    --border \
+    --prompt="Session> " \
+    --preview="tmux_pane_tree {}" \
+    --preview-window=right:99% \
+    --print-query
+}
+
+_fzf_tmux_attach_start_session() {
   if [ -z "$1" ]; then
-    result=$(
-      tl | fzf \
-        --layout=reverse \
-        --height=50% \
-        --border \
-        --prompt="Session> " \
-        --preview="tmux_pane_tree {}" \
-        --preview-window=right:99% \
-        --print-query
-    )
+    result=$(_fzf_tmux_list_sessions)
     case "$?" in
     0)
       # found a session, attaching