tm, the Session Picker

tm is Cole’s way back into tmux: type two letters and an fzf picker lists every session on the machine, most recently used first, with a “new session” entry pinned on top. Pick one and you are attached. Cole describes it as a “custom picker using FZF, which automatically lists our most recent tmux sessions with a cache and all that”. It is built to be the first thing you type after logging in to a machine, from the desktop or from a phone.

What it looks like

tmux>
  [+ new session]
  site: 6 windows (created Tue Oct 27 21:14:02 2026) (attached)
  agents: 23 windows (created Mon Oct 26 08:02:41 2026)
  notes: 2 windows (created Sun Oct 25 19:40:13 2026)

The picker opens right below the prompt, 40 percent of the terminal tall, and lists sessions top-down. Type a few letters to filter, use the arrow keys to move, press Enter to attach, or Esc to back out without doing anything. Each line is the session’s own tmux ls entry, so the window count and the attached marker come for free.

fzf does the picking. It is a general-purpose fuzzy finder: any list piped into it becomes a searchable menu, and whatever line you choose comes out on standard output. tm is a short shell function around it, in Cole’s base/aliases.sh:

    selected=$(printf '%s\n%s\n' "$new_item" "$ordered" \
        | fzf --height=40% --reverse --prompt="tmux> ")

How the ordering works

The useful part is the order. The session you were just in should be first, the one before that second, and so on. tm scores each session with the larger of two timestamps:

1. tmux’s own record. tmux keeps #{session_last_attached}, the time any client last attached to each session. It updates however you attach: through tm, through tl, with a plain tmux attach, or from an editor.
2. The picks log. Every pick through tm appends one line, the current time and the session name, to ~/.cache/tm/picks. This is the cache Cole mentions. It covers the one case tmux cannot: a brand-new session you just named, which tmux has not recorded an attach for yet.

Taking the maximum means neither signal can go stale. Sessions that were never attached score zero and sort to the bottom, alphabetically. The log is trimmed to its last 200 lines on every pick, so it never grows. The sorting itself is one awk pass plus a numeric sort, fast enough that the picker appears instantly even with dozens of sessions.

New sessions

The top entry, [+ new session], asks for a name. If a session by that name already exists, tm attaches to it; otherwise it creates one. Naming sessions after what they hold (a project, a client, a long job) makes the picker read like a table of contents.

tl: the last session, no picker

tl skips the menu and attaches to whichever session tmux saw attached most recently:

tl() {
    local target
    target=$(tmux list-sessions -F '#{session_last_attached} #{session_name}' 2>/dev/null \
        | sort -k1,1nr | head -1 | cut -d' ' -f2-)

It goes on to check $TMUX: inside tmux it switches the current client to that session instead of trying to nest one tmux inside another. Outside, it attaches. After a disconnect, tl is the fastest way back to exactly where you were.

Safe for scripts and agents

When tm is not talking to a terminal, because its input or output is a pipe or an agent’s shell, it skips the picker and just prints the tmux ls list, or “No tmux sessions”. An agent that runs tm to look around gets a list instead of hanging on a menu nobody can see.

Gotcha: inside tmux, use tl or the Alt keys

tm always attaches with tmux attach. From inside a tmux pane, tmux refuses that: running it on tmux 3.7 stops with “sessions should be nested with care, unset $TMUX to force”. Inside tmux, switch with tl, prefix s for the session chooser, or Alt+s to cycle sessions (see the The tmux Keymap). If you copy tm into your own setup, borrowing tl’s $TMUX check and calling switch-client there removes the trap.

Where it fits

• On the phone. From Termius, over Tailscale and SSH, tm is the shortest path from “connected” to “looking at the agent I left running”. The picker fits a phone screen.
• With the status line. Once attached, the second row of the tmux status line lists every session, so a picker is only needed to get in.
• With agents. Sessions created by Parallel Worktrees or parked by cc-park show up in the list like any other, so returning to a fan-out of ten agents is tm and Enter.

Set it up

1. Install fzf: brew install fzf on a Mac (Homebrew and the Brewfile) or sudo apt install fzf on Debian and Ubuntu. Cole’s installer puts it on every machine.
2. Copy the tm and tl functions from base/aliases.sh into your shell config, or install the whole shell component of Cole’s dotfiles.
3. Open a new shell and type tm.

The yu and the Claude Launchers page covers the other one-word commands in the same file, the ones that start agents.