Editing Software Development Platforms (section)

==Scripts to Set Environment Variables==

If you want to use different versions of installed software, or not have everything on your path all the time, it is convenient to use scripts to modify the environment variables.  For convenience, here is a script that provides some useful functions for modifying paths.  I name it setenv_functions.sh and put it in /usr/local/bin.
----
<source lang=bash>
#!/bin/bash
#
# setenv_functions.sh
#
# Eric Nodwell, January 2011
#
# Provides functions useful for modifying system paths.
#
# You call this from other bach scripts like this:
#
#    source /usr/local/bin/setenv_functions.sh
#
# Then you can make use of the functions defined below.
#  
# Example usage: add_path PATH /usr/my/path
#
function add_path
{
  echo -e "Adding to ${1}: \033[1;34m${2}\033[0m"
  eval "OLDLIST=\"\$$1\""
  if [ -n "${OLDLIST}" ] ; then
    eval "$1=\"$2:\$$1\""
  else
    eval "$1=\"$2\""
  fi
  eval "export $1"
}
 
# Example usage: remove_path PATH /usr/my/path
#
# The second argument can be a regular expression for pattern matching.
#
function remove_path
{
  eval "OLDLIST=\"\$$1\""
  REMOVALLIST=$( echo ${OLDLIST} | tr -s ":" "\n" | grep -wE "${2}" | tr -s "\n" ":" | sed "s/:$//" )
  if [ -n "${REMOVALLIST}" ] ; then
    echo -e "Removing from ${1}: \033[1;31m${REMOVALLIST}\033[0m"
    NEWLIST=$( echo ${OLDLIST} | tr -s ":" "\n" | grep -vwE "${2}" | tr -s "\n" ":" | sed "s/:$//" )
    eval "$1=\"$NEWLIST\""
    eval "export $1"
  fi
}
 
# Example usage: check_path PATH /usr/my/path
#
# The second argument can be a regular expression for pattern matching.
#
function check_path
{
  eval "OLDLIST=\"\$$1\""
  CHECKLIST=$( echo ${OLDLIST} | tr -s ":" "\n" | grep -wE "${2}" | tr -s "\n" ":" | sed "s/:$//" )
  test -n "${CHECKLIST}"
  return $?
}
# Example usage: add_path PATH /usr/my/path
#
function add_path
{
  echo -e "Adding to ${1}: \033[1;34m${2}\033[0m"
  eval "OLDLIST=\"\$$1\""
  if [ -n "${OLDLIST}" ] ; then
    eval "$1=\"$2:\$$1\""
  else
    eval "$1=\"$2\""
  fi
  eval "export $1"
}

# Example usage: remove_path PATH /usr/my/path
#
# The second argument can be a regular expression for pattern matching.
#
function remove_path
{
  eval "OLDLIST=\"\$$1\""
  REMOVALLIST=$( echo ${OLDLIST} | tr -s ":" "\n" | grep -wE "${2}" | tr -s "\n" ":" | sed "s/:$//" )
  if [ -n "${REMOVALLIST}" ] ; then
    echo -e "Removing from ${1}: \033[1;31m${REMOVALLIST}\033[0m"
    NEWLIST=$( echo ${OLDLIST} | tr -s ":" "\n" | grep -vwE "${2}" | tr -s "\n" ":" | sed "s/:$//" )
    eval "$1=\"$NEWLIST\""
    eval "export $1"
  fi
}

# Example usage: check_path PATH /usr/my/path
#
# The second argument can be a regular expression for pattern matching.
#
function check_path
{
  eval "OLDLIST=\"\$$1\""
  CHECKLIST=$( echo ${OLDLIST} | tr -s ":" "\n" | grep -wE "${2}" | tr -s "\n" ":" | sed "s/:$//" )
  test -n "${CHECKLIST}"
  return $?
}
</source>
----

There will be several examples below making use of this script.  See for example [[#asciidoc|asciidoc]] , where a script /opt/asciidoc-8.6.3/setenv.sh is created .  You use it like this:

 source /opt/asciidoc-8.6.3/setenv.sh

The output will look something like:

 Adding to DYLD_LIBRARY_PATH: /opt/boost-1.45.0/lib
 Adding to PATH: /opt/source-highlight-3.1.4/bin
 Adding to DYLD_LIBRARY_PATH: /opt/source-highlight-3.1.4/lib
 Adding to PATH: /opt/dblatex-0.3/bin
 Adding to PYTHONPATH: /opt/dblatex-0.3/lib/python2.7/site-packages
 Adding to PATH: /opt/asciidoc-8.6.3/bin