Bash – RVM + TMUX—Duplicate entries in $PATH

bashbashrctmux

My Linux terminal config files (.bash_profile, .profile, .bashrc) expand $PATH by prepending some custom directories. This only happens once (and I've also included some ENV vairiable based guards to enforce that it can only ever happen once). My .bash_profile also sources the .rvm script (~/.rvm/scripts/rvm) which prepends its own custom dirs. These RVM dirs must be first.

Everything's OK as long as I'm in a clean bash session.

If I run tmux, however, the directory entries from my config files get prepended to PATH doubly (regardless of my ENV variable guards). It seems that tmux has two environments for ENV variables which it then merges.

This is a problem, since entries prepended by the .rvm script get only prepended once, and in the tmux scenario they don't end up first.

How can I prevent this from happening?

Edit—additional info:
All my PATH additions get prepended in .profile, which I include from .bash_profile (. ~/.profile). All my GUI terminals are run "as a login shell".

In each config file, I use guards of the following form to prevent double inclusion:

    if [ "$PROFILE_SOURCED" != "true" ]; then
         export PROFILE_SOURCED=true
    ...
    fi

By prepending an entry to PATH, I mean export PATH=entry:$PATH.

Best Answer

Solved by the following:

Placed a guard around my PATH manipulation code in .profile

if [ "$PATHS" != "true" ]; then
    export PATHS="true"
#Manipulate and export PATH over here
fi

Removed file-level guards around .bash_profile and .bashrc
IMPORTANT: RESTARTED the tmux server. (killall tmux) -- the manual indicates the server maintains its own environment, which it inherits from its parent shell. If config files change, tmux needs to start afresh.

Related Solutions

Bash – Are Duplicate Entries in $PATH a Problem?

Having more entries in $PATH doesn't directly slow your startup, but it does slow each time you first run a particular command in a shell session (not every time you run the command, because bash maintains a cache). The slowdown is rarely perceptible unless you have a particularly slow filesystem (e.g. NFS, Samba or other network filesystem, or on Cygwin).

Duplicate entries are also a little annoying when you review your $PATH visually, you have to wade through more cruft.

It's easy enough to avoid adding duplicate entries.

case ":$PATH:" in
  *":$new_entry:"*) :;; # already there
  *) PATH="$new_entry:$PATH";; # or PATH="$PATH:$new_entry"
esac

Side note: sourcing someone else's shell script means executing code that he's written. In other words, you're giving your friends access to your account whenever they want.

Side note: .bashrc is not the right place to set $PATH or any other environment variable. Environment variables should be set in ~/.profile. See Which setup files should be used for setting up environment variables with bash?, Difference between .bashrc and .bash_profile.

Bash – Remove duplicate $PATH entries with awk command

If you don't already have duplicates in the PATH and you only want to add directories if they are not already there, you can do it easily with the shell alone.

for x in /path/to/add …; do
  case ":$PATH:" in
    *":$x:"*) :;; # already there
    *) PATH="$x:$PATH";;
  esac
done

And here's a shell snippet that removes duplicates from $PATH. It goes through the entries one by one, and copies those that haven't been seen yet.

if [ -n "$PATH" ]; then
  old_PATH=$PATH:; PATH=
  while [ -n "$old_PATH" ]; do
    x=${old_PATH%%:*}       # the first remaining entry
    case $PATH: in
      *:"$x":*) ;;          # already there
      *) PATH=$PATH:$x;;    # not there yet
    esac
    old_PATH=${old_PATH#*:}
  done
  PATH=${PATH#:}
  unset old_PATH x
fi

Best Answer

Related Solutions

Bash – Are Duplicate Entries in $PATH a Problem?

Bash – Remove duplicate $PATH entries with awk command

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