Fix the mess that /usr/libexec/path_helper made of my $PATH

fixpaths.sh

#!/bin/sh

#Reorders $PATH, removes duplicates

prefixes="$1"
if [ '--' = "$prefixes" ]; then
    shift;
    prefixes="$1";
else
    if echo "$prefixes" | grep -q '^\(\|--help\|-h\)$' ; then
        echo "USAGE: pathfix.sh [--] PREFIXLIST [PATHLIST]"
        echo "Arguments:"
        echo "   PREFIXLIST  a colon separated list of path prefixes, required"
        echo "   PATHLIST    a colon separated list of paths, defaults to \$PATH"
        echo;
        echo "Elements in PATHLIST which begin with a prefix from PREFIXLIST"
        echo "are brought forward. Duplicates are removed."
        echo "New colon separated list is sent to STDOUT"
        echo;
        echo "Example: "
        echo "  pathfix.sh '/sw:/usr' '/bin/:/usr/local/bin:/bin:/sw/bin'"
        echo "  returns: /sw/bin:/usr/local/bin:/bin"
        echo;
        exit 1;
    fi
fi;

pathlist="$2";
if [ -z "$pathlist" ]; then
    pathlist="$PATH";
fi

newpath='';
oldpath=":$pathlist";
OIFS="$IFS"
IFS=':'
for o in $prefixes; do
    told=`echo "$oldpath"| cut -c 2-`
    oldpath='';
    for p in $told; do
        p=`echo "$p"|sed 's:/$::'`;
        if echo "$p"|grep -q "^$o"; then
            echo ":$newpath:" | grep -q ":$p:" || \
                newpath="$newpath:$p";
        else
            echo ":$oldpath:" | grep -q ":$p:" || \
                oldpath="$oldpath:$p";
        fi
    done
done
IFS="$OIFS"
newpath="$newpath$oldpath";
echo "$newpath"| cut -c 2-;

It would be trivial to have the list of prefixes be specified as a parameter and to return the new path list. This would make the script reusable and not require "sourcing" it. For example

 . ./fixpaths.sh

would become

 PATH=`fixpaths.sh '/Users/:/sw/:/usr/local'`

So trivial that I fixed it.