Add Set Environment Variables When Creating Session as a tmux til

Author: jbranchaud

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1177 TILs and counting..._
+_1178 TILs and counting..._
 
 ---
 
@@ -1064,6 +1064,7 @@ _1177 TILs and counting..._
 - [Remove The Delay On The Escape Key](tmux/remove-the-delay-on-the-escape-key.md)
 - [Rename The Current Session](tmux/rename-the-current-session.md)
 - [Reset An Option Back To Its Default Value](tmux/reset-an-option-back-to-its-default-value.md)
+- [Set Environment Variables When Creating Session](tmux/set-environment-variables-when-creating-session.md)
 - [Set Session Specific Environment Variables](tmux/set-session-specific-environment-variables.md)
 - [Show The Current Value For An Option](tmux/show-the-current-value-for-an-option.md)
 - [Swap Split Panes](tmux/swap-split-panes.md)

tmux/set-environment-variables-when-creating-session.md

@@ -0,0 +1,24 @@
+# Set Environment Variables When Creating Session
+
+In [Set Session-Specific Environment
+Variables](set-session-specific-environment-variables.md), I showed how env
+vars that are scoped to a tmux session can be set in an existing session.
+
+It is also possible to set any number of environment variables when creating a
+session. This is particularly handy if you are scripting the setup of various
+tmux environments.
+
+A base command to start a tmux session might look like this:
+
+```bash
+$ tmux new -s my-project
+```
+
+To set environment variables on that session, use one or more `-e` flags
+followed by the name and value.
+
+```bash
+$ tmux new -s my-project -e EDITOR=code -e PG_VERSION=13.4
+```
+
+See `man tmux` for more details.