| Re: System Variable Behavior Changed in IDL 6.0 [message #38616 is a reply to message #38474] |
Thu, 11 March 2004 13:07  |
Michael Wallace
Messages: 409
Registered: December 2003
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Senior Member |
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> just create two soft links:
>
> ln -s /usr/local/rsi/idl_5.5/bin/idl /usr/local/bin/idl55
> ln -s /usr/local/rsi/idl_6.0/bin/idl /usr/local/bin/idl60
>
> and use the idl55 and idl60 commands (idl is a script itself, which sets
> the appropriate env. variables).
In this case, you still have the issue of what IDL_PATH is set to. If
left unset, the soft links solution you suggest will work. IDL will
automagically determine the correct lib directory to use.
However, almost all of us have to explicitly set IDL_PATH in order to
include our own libraries and other procedures. Because of this we are
forced to choose between the $RSI_DIR/idl_5.5/lib directory and the
$RSI_DIR/idl_6.0/lib directories. And you can't set IDL_PATH to include
both directories since one will clobber the other.
So, with that in mind, the better solution is to symlink the IDL
directories rather than the executables. By using a symlink that points
to idl_5.5 or idl_6.0 or other directory, we don't have the IDL_PATH
issue because we just have to only include $RSI_DIR/idl/lib in IDL_PATH.
So, all we have to do is change the symlink and we're ready to go.
I hacked up a quick little script in the last few minutes to do the
recreation of the symlink for us. I make no guarantees about the
quality. I show it here as an example only.
#!/bin/bash
#
# Usage: switchidl version_number
#
# Example: switchidl 5.6
#
# This script will recreate the idl symlink on systems where multiple
# versions of IDL are installed. Two assumptions are made:
# 1. All IDL installations are in the $RSI_DIR directory
# 2. All IDL installations are in directories of the form idl_xxx
# where xxx is the version number
#
# If RSI_DIR is not set, use the IDL default
if [ ! -n "$RSI_DIR" ]; then
RSI_DIR=/usr/local/rsi
fi
# Check for the version number argument
if [ ! -n "$1" ]; then
echo Usage: switchidl version_number
exit 1
fi
# Check if requested IDL directory exists
if [ ! -e $RSI_DIR/idl_$1 ]; then
echo IDL $1 could not be found
exit 2
fi
# Check if IDL symlink already exists
if [ -e $RSI_DIR/idl ]; then
# Delete the symlink, if possible
if [ -w $RSI_DIR/idl ]; then
rm $RSI_DIR/idl
else
echo Incorrect permissions -- could not alter symlink
exit 3
fi
else
# Check if it's possible to write to $RSI_DIR
if [ ! -w $RSI_DIR ]; then
echo Incorrect permissions -- could not alter symlink
exit 3
fi
fi
# All checks are satisfied
# Move to $RSI_DIR, create the link and return
owd=`pwd`
cd $RSI_DIR
ln -s idl_$1 idl
cd $owd
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