Open new Terminal tabs from the command line

tab.bash

#!/bin/bash
#
# Open new Terminal tabs from the command line
#
# Author: Justin Hileman (http://justinhileman.com)
#
# Installation:
#     Add the following function to your `.bashrc` or `.bash_profile`,
#     or save it somewhere (e.g. `~/.tab.bash`) and source it in `.bashrc`
#
# Usage:
#     tab                   Opens the current directory in a new tab
#     tab [PATH]            Open PATH in a new tab
#     tab [CMD]             Open a new tab and execute CMD
#     tab [PATH] [CMD] ...  You can prob'ly guess

# Only for teh Mac users
[ `uname -s` != "Darwin" ] && return

function tab () {
    local cmd=""
    local cdto="$PWD"
    local args="$@"

    if [ -d "$1" ]; then
        cdto=`cd "$1"; pwd`
        args="${@:2}"
    fi

    if [ -n "$args" ]; then
        cmd="; $args"
    fi

    osascript &>/dev/null <<EOF
        tell application "iTerm"
            tell current terminal
                launch session "Default Session"
                tell the last session
                    write text "cd \"$cdto\"$cmd"
                end tell
            end tell
        end tell
EOF
}

tab.fish

# Open new iTerm and Terminal tabs from the command line
#
# Author: Justin Hileman (http://justinhileman.com)
#
# Usage:
#     tab                   Opens the current directory in a new tab
#     tab [PATH]            Open PATH in a new tab
#     tab [CMD]             Open a new tab and execute CMD
#     tab [PATH] [CMD] ...  You can prolly guess

function tab -d "Open the current directory in a new tab"
  set -l cmd ""
  set -l cdto (pwd)

  if test (count $argv) -gt 0
    pushd . >/dev/null
    if test -d $argv[1]
      cd $argv[1]
      set cdto (pwd)
      set -e argv[1]
    end
    popd >/dev/null
  end

  if test (count $argv) -gt 0
    set cmd "; $argv"
  end

  switch $TERM_PROGRAM

  case 'iTerm.app'
    osascript 2>/dev/null -e "
      tell application \"iTerm\"
        tell current terminal
          launch session \"Default Session\"
          tell the last session
            write text \"cd \\\"$cdto\\\"$cmd\"
          end tell
        end tell
      end tell
    "

  case 'Apple_Terminal'
    osascript 2>/dev/null -e "
      tell application \"Terminal\"
        activate
        tell application \"System Events\" to keystroke \"t\" using command down
        repeat while contents of selected tab of window 1 starts with linefeed
          delay 0.01
        end repeat
        do script \"cd \\\"$cdto\\\"$cmd\" in window 1
      end tell
    "

  case '*'
    echo "Unknown terminal: $TERM_PROGRAM" >&2
  end
end

@newplasticideas there are currently bash and fish implementations. it's possible to port this to zsh as well, but if you're going to do that, i'd suggest starting with https://github.com/oh-my-fish/plugin-tab which has been updated more recently and supports a lot more terminals :)

ITerm2's Applescript is deprecated. Take a look at the Python API and this example: https://iterm2.com/python-api/tutorial/example.html