Tag: tmux

To reorder windows in tmux, you can use following command

CTRL + B + .

Press CTRL + B or whatever prefix you use, then press . (dot). This will ask you number/position where you need current window moved.

Another method is

CTRL + B + :

This will give you tmux command promt. Now enter

move-window -t 0

This will move current window to position 0. This only work if position 0 is empty. If another window already present in position 0, use swap-window command.

swap-window -t 0

This with swap current window with window in position 0.

Another useful command is

CTRL + B + ,

This will allow you to rename current tmux window.

Using shortcuts

You can edit .tmux.conf file and add following

bind-key -n C-S-Left swap-window -t -1
bind-key -n C-S-Right swap-window -t +1

Now you can use CTRL + SHIFT + LEFT OR RIGHT arrow to move windows.

See tmux

If you want to run same command on multiple servers, you can use tmux synchronize-panes feature. This will be useful when you need to setup multiple servers, say install nginx/php/mysql on multiple servers.

You can create multiple panes in tmux. SSH into each of the servers from these panes. Now run

CTRL + B :

Now type

setw synchronize-panes on

Whatever command you run on one of the pane will be executed on all panes. Be careful when you run server specific commands.

When you start a new window or split pane on tmux, it always start with the directory from where you run tmux command.

I prefer it start with current working directory of active tmux window. To do this, edit file

vi ~/.tmux.conf

Add

bind c new-window -c "#{pane_current_path}"
bind '"' split-window -c "#{pane_current_path}"
bind % split-window -h -c "#{pane_current_path}"

To start tmux and attach to existing connection on SSH in, edit file

vi ~/.bashrc

Add

if [[ "$TMUX" == "" ]] && [[ "$SSH_CONNECTION" != "" ]] && [ "$SSH_TTY" != "" ]; then
    WHOAMI=$(whoami)
    if tmux has-session -t $WHOAMI 2>/dev/null; then
        tmux -2 attach-session -t $WHOAMI
    else
        tmux -2 new-session -s $WHOAMI
    fi
fi

Method 2

You can use following command when connecting to remote sevrer.

ssh  USER@SERVER_IP -t tmux a

Most of the time i connect to remote virtial machine to SSH to other servers. This way i will always have a fixed IP, so i can white list my IP in firewall. I use tmux on this server, so even if i get disconnected, my connection to these servers won’t get disconnected. This is useful when you running some commands that take long to finish.

On this VPS, i don’t keep my SSH keys for security reason, instead i use SSH Agent forwarding with ssh -A option. From my PC, i connect to sshbox with command

ssh -A root@IP_OF_VM

If i start a new tmux session, i will be able to login to other servers using my SSH key. If i attach to pre extsing tmux session, my SSH key won’t work. This is because SSH Agent use an environment variable SSH_AUTH_SOCK, this point to a sock file. When you get disconnected, it get deleted.

To fix this problem, edit ~/.tmux.conf file

vi ~/.tmux.conf

Add

set-environment -g 'SSH_AUTH_SOCK' ~/.ssh/ssh_auth_sock

Create file

vi ~/.ssh/rc

with following content

if [ ! -S ~/.ssh/ssh_auth_sock ] && [ -S "$SSH_AUTH_SOCK" ]; then
    ln -sf $SSH_AUTH_SOCK ~/.ssh/ssh_auth_sock
fi

~/.ssh/rc file get executed every time a user connect using SSH. It will set symlink to SSH_AUTH_SOCK location if SSH agent forwarding is enabled.

• Auto Attach to tmux session on SSH
• SSH Agent forwarding with tmux
• tmux create new window on current directory
• run same command on multiple tmux panes
• Reorder windows in tmux

To attach to a specific session, run

tmux a -t SESSION_ID

.tmux.conf

.tmux.conf file is used to configure tmux

Here is the .tmux.conf i use

https://gist.github.com/serverok/f8f729e2c22a5ab1fa6b0d82765bcddc

If you change this file, you need to restart the terminal or run

tmux source-file .tmux.conf

Scroll Mode in tmux

To scroll, you need to enter scroll mode by pressing

CTRL + B, then press PageUp key.
CTRL + B, then [

To exit scroll mode, press q