Why do I get duplicated entries in my $PATH?

Question

I'm using Ubuntu 9.10 (karmic). And, my ~/.pam_environment looks like the following.

PATH            DEFAULT=${PATH}:~/Adobe/Reader9/bin:~/texlive/2009/bin/x86_64-linux
GIT_EDITOR      DEFAULT=vim
MANPATH         DEFAULT=${MANPATH}:~/texlive/2009/texmf/doc/man
INFOPATH        DEFAULT=${INFOPATH}:~/texlive/2009/texmf/doc/info

But, echo $PATH returns me duplicated entries as the following.

/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:~/Adobe/Reader9/bin:~/texlive/2009/bin/x86_64-linux:~/Adobe/Reader9/bin:~/texlive/2009/bin/x86_64-linux

I've tried replacing DEFAULT by OVERRIDE in my ~/.pam_environment file. But, that didn't help.

Does any one know what's wrong with my ~/.pam_environment?

Answer 1

The problem seems to stem from the fact that pam_env defaults to reading the user ~/.pam_environment every time it is invoked. A lot of login methods (cron, lightdm, lightdm-autologin, login, sshd and su on my machine) invoke pam_env twice: once to read the /etc/environment and ~/.pam_environment files, and once to read the /etc/default/locale file. In neither case is the user_readenv flag set, so pam_env reads, and acts on, your ~/.pam_environment twice.

To fix this, go to your /etc/pam.d directory, and add the following to every line in which pam_env is invoked with the envfile=/etc/default/locale option:

user_readenv=0

Answer 2

Check your /etc/pam.d/ that pam_env.so isn't loaded twice somehow, such as both in session and in auth.

Answer 3

Not an answer, exactly, but possibly useful to others who have duplication issues

---

Starting from the accept answer I received on from Stack Overflow: How do I manipulate $PATH elements in shell scripts? I have developed a slightly large set of tools. Most of the credit here should go to Jonathan Leffler who provided the model I used in writing these.

Add without duplicating

# Insure that a path element exists by adding it to the end if it does not
#
#   $1 name of the shell variable to set (e.g. PATH)
#   $3 the path element that we want to insure exists
function insure_path () {
    local path=$1
    local list=$(eval echo '$'$path)
    local pat=$2

    checkstr=$(echo "$list" | tr ":" "\n" | grep -Fm 1 "$pat")
    if [ "$checkstr" ] 
    then
        true
    else
        export $path=$(echo $list:$pat | sed -e 's|\(:\):*|\1|g' -e 's|:$||' -e'
s|^:||')
    fi
}

# Insure that a path element exists by adding it to the front if it does not
#
#   $1 name of the shell variable to set (e.g. PATH)
#   $2 the path element that we want to insure exists
function insure_path_front () {
    local path=$1
    local list=$(eval echo '$'$path)
    local pat=$2

    checkstr=$(echo "$list" | tr ":" "\n" | grep -Fm 1 "$pat")
    if [ $checkstr ] 
    then
        true
    else
        export $path=$(echo $pat:$list | sed -e 's|\(:\):*|\1|g' -e 's|:$||' -e'
s|^:||')
    fi
}

Remove existing duplicates

# Remove duplicates from a path. Preferes the ealiest instance of each
# duplicate because this preserves the semantics of the existing path
#
#   $1 name of the shell variable to set (e.g. PATH)
function unduplicate_path () {
    local path=$1
    local list=$(eval echo '$'$path)
    local split_list=$(echo "$list" | tr ":" " ")
    local tempp=""
    # Build the new version of $path from scrath
    for p in $split_list
    do
        insure_path_back tempp $p
    done
    # Now replace the existing version
    export $path=$tempp
}