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I just tried rails inside a tmux session in iTerm2 and it returns as

-bash: /usr/bin/rails: /usr/bin/ruby: bad interpreter: No such file or directory

I can run rails outside of tmux . I am using Mac OSX. I've installed Ruby via RVM . Here's the output of ruby -v

ruby 1.9.3p392 (2013-02-22 revision 39386) [x86_64-darwin12.3.0]

and which ruby


It's the same output for both inside tmux and normal bash shell.

Here's my ~/.tmux.conf

set -g default-terminal "screen-256color"

How am I able to run rails inside the tmux session?

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up vote 2 down vote accepted

Ensure that the bash session inside tmux is running as an interactive shell; the -i option to bash will start it in this mode. If I recall correctly, the RVM script runs from .bashrc, which is only executed for interactive shells; since it's the RVM script which adds ~/.rvm/... to your path, if it's not running, then bash will not be looking in the right place for the Ruby interpreter.

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you mean adding -i option to tmux new -s new-tmux in the bash shell ? sorry. I am new to these stuff. – Ye Lin Aung May 7 '13 at 15:28
I don't use Tmux on a regular basis, so can't give as good advice here as I like. But based on the testing I've just done, you'd need to add set-option -g default-command "/bin/bash -i" as a line in your ~/.tmux.conf to ensure that bash starts in interactive mode. – Aaron Miller May 7 '13 at 15:44
It seems working now. But I see a couple of bash: preexec_invoke_exec: command not found lines and it seems annoying and bash becomes like bash-3.2$ . Here's the pic. Any ways to fix it ? – Ye Lin Aung May 8 '13 at 0:55
Not off the top of my head, but this has some more information on the preexec_invoke_exec hook, which may be of help. – Aaron Miller May 8 '13 at 15:02

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