Yes, at the end of your .bash_profile, put the line:
. ~/.bashrc
This automatically sources the rc file under those circumstances where it would normally only process the profile.
The rules as to when bash runs certain files are complicated, and depend on the type of shell being started (login/non-login, interactive or not, and so forth), along with command line arguments and environment variables.
You can see them in the man bash output, just look for INVOCATION - you'll probably need some time to digest and decode it though :-)
Former answers provided solutions but didn't explain the reason. Here it is.
This is related to the Bash init files. By default, ~/.bashrc is used in an interactive, non-login shell. It won't be sourced in a login shell. Tmux uses a login shell by default. Hence, shells started by tmux skip ~/.bashrc.
default-command shell-command
The default is an empty string, which instructs tmux to create a login shell using the value of the default-shell option.
Init files for Bash,
login mode:
/etc/profile
~/.bash_profile, ~/.bash_login, ~/.profile (only first one that exists)
interactivenon-login:
/etc/bash.bashrc (some Linux; not on Mac OS X)
~/.bashrc
non-interactive:
source file in $BASH_ENV
The weird interactive, non-login loading requirement confuses people in other situations as well. The best solution is to change the loading requirement of ~/.bashrc as interactive only, which is exactly what some distros, like Ubuntu, are doing.
# write content below into ~/.profile, or ~/.bash_profile
# if running bash
if [ -n "$BASH_VERSION" ]; then
# include .bashrc if it exists
if [ -f "$HOME/.bashrc" ]; then
. "$HOME/.bashrc"
fi
fi
This should be the solution you desire. And I recommend every Bash user setup this in the profile.