tmux: run clipboard script in posix shell to overcome file permission issue

Author: davidandreoletti

.tmux.conf

@@ -224,7 +224,7 @@ if-shell 'expr $TMUX_VERSION \< 2.4' \
     "bind-key -t vi-copy v rectangle-toggle'"  # switch between line and columnwise selection
 
 # Re-copy tmux buffer to macOS/linux system clipboard
-bind y run-shell "tmux show-buffer | ~/.bin/clipboard --to-system && tmux display-message \"COPIED: tmux buffer > system clipboard\" || tmux display-message \"FAILED: tmux buffer > system clipboard\""
+bind y run-shell "tmux show-buffer | sh ~/.bin/clipboard --to-system && tmux display-message \"COPIED: tmux buffer > system clipboard\" || tmux display-message \"FAILED: tmux buffer > system clipboard\""
 
 # Clear shell terminal and tmux history at once like Terminal's Cmd+k
 # Inspired from: http://stackoverflow.com/questions/10543684/how-can-i-clear-scrollback-buffer-in-tmux