tmux and It's Extension smux

tmux is short for Terminal MUltipleXer and, conceptually, lets you "split" one terminal into many different terminals. It is a very powerful program with a lot of different features, below I have simply listed two resources I've found helpful.

tmux Cheat Sheet for remembering how to do certain things
tmux Wiki on GitHub is helpful for learnign the vocabulary and how to use it

One of the features that tmux offers is the ability to "detach" from a terminal session and allow the program to continue running in the background. This is very helpful when connected with ssh, allowing us to go to the cluster, start a program that takes a long time to run, detach from that terminal, disconnect from ssh, and only reconnect when we want to check on our long-running program. This ssh+tmux workflow is so common for me that I wrote a small bash wrapper connecting the two called smux.

Below, I have copied the bash code which I've been using for a few years now. Feel free to put it in your .bashrc or some other file for later use. I've also isolated it into a POSIX-compliant shell executable on GitHub which is light enough to install into your home directory pretty much anywhere.

curl -s https://raw.githubusercontent.com/tomeichlersmith/smux/main/install | sh

smux

#!/bin/bash

# ssh+tmux = smux

__smux_help() {
  cat <<\HELP

  Using ssh and tmux on remote computers.

  NOTE: <TAB> completion for smux only works after it is attempted for ssh.

 USAGE: 
  smux [-h|--help] [-l|--list] <host> [session]

 OPTIONS:
  -h|--help : print this help and exit
  -l|--list : list the sessions on the input host and exit

 ARGUMENTS:
  host      : (required) hostname of computer you wish to attach to
  session   : (optional) name of session to attach to on the input host 

HELP
}
__smux_list() {
  local _host="$1" #required
  ssh -t ${_host} "tmux ls 2> /dev/null"
  return $?
}
__smux_attach() {
  local _host="$1" #required
  local _session="$2" #optional
  ssh -t ${_host} "tmux attach ${_session:+-t} ${_session} || tmux new ${_session:+-s} ${_session}"
  return $?
}
smux() {
  case "$1" in
    ""|-h|--help)
      __smux_help
      return 0
      ;;
    -l|--list)
      __smux_list "$2"
      return 0
      ;;    
    -*)
      echo "ERR: Unknown option $1"
      return 1
      ;;
  esac
  
  __smux_attach "$1" "$2"
  return $?
}

__complete_smux() {
  if ! hash _ssh &> /dev/null; then
    # __load_completion is a bash internal that is used
    #   to expand the tab completion set of functions if
    #   no function is defined
    #   it defines the ssh completion function _ssh
    __load_completion ssh || return $?
  fi 

  # disable readline filename completion
  compopt +o default

  local __curr_word="${COMP_WORDS[$COMP_CWORD]}"

  if [[ "$COMP_CWORD" == "1" ]]; then
    if [[ "${__curr_word}" == -* ]]; then
      # option
      COMPREPLY=($(compgen -W "-h --help -l --list" -- "${__curr_word}"))
    else
      # host, use ssh tab completion
      _ssh
      return $?
    fi
  else
    case "${COMP_WORDS[1]}" in
      -l|--list)
        # shift inputs so _ssh tab complete works
        COMP_WORDS=(${COMP_WORDS[@]:1})
        COMP_CWORD=$((COMP_CWORD - 1))
        _ssh
        return $?
        ;;
      *)
        # no other tab complete implemented,
        #   we /could/ try tab completing tmux sessions on the host
        #   that is already selected, but that would make tab complete
        #   slow since it would have to ssh there to find out the list
        COMPREPLY=()
        ;;
    esac
  fi
}
complete -F __complete_smux smux

UMN SPA Cluster

tmux and It's Extension smux

smux