--- title: Why is Tmux crashing on start? author: James type: post date: 2018-11-07T07:40:45+00:00 url: /2018/11/07/why-is-tmux-crashing-on-start/ medium_post: - 'O:11:"Medium_Post":11:{s:16:"author_image_url";N;s:10:"author_url";N;s:11:"byline_name";N;s:12:"byline_email";N;s:10:"cross_link";s:2:"no";s:2:"id";N;s:21:"follower_notification";s:3:"yes";s:7:"license";s:19:"all-rights-reserved";s:14:"publication_id";s:2:"-1";s:6:"status";s:4:"none";s:3:"url";N;}' categories: - Open Source tags: - linux - script - tmux --- I spent several hours trying to get to the bottom of why tmux was crashing as soon as I ran it on Fedora. It turns out there’s a simple fix. When tmux starts it uses /dev/ptmx to create a new TTY (virtual terminal) that the user can interact with. If your user does not have permission to access this device then tmux will silently die. A good way to verify this is to try running [screen][1] too. In my case I realised that my user was not a member of the user group “tty” on my system. The answer was therefore simple: 
sudo usermod -a -G tty james
I hope this helps someone avoid spending hours searching for the right incantation. [1]: https://en.wikipedia.org/wiki/GNU_Screen