quite simple tool version selector (bash-based)

tool.bash

#!/usr/bin/env bash

SCRIPT_CALL=${BASH_SOURCE[0]}
SCRIPT_REAL=$(realpath $SCRIPT_CALL)

name=$(basename $SCRIPT_REAL)
ver_name=${name^^}_VER
ver_default_name=${ver_name}_DEFAULT

ver_default=${ver_default_name}
ver=${!ver_name:-${!ver_default_name}}

opt=$(dirname $SCRIPT_REAL)/../opt
bin=bin/$(basename $SCRIPT_CALL)

if [ -d $opt/$name-$ver ]
then $opt/$name-$ver/$bin "$@"
else
    pat="$opt/$name-${ver}*/$bin"
    if [ "$(eval ls $pat | wc -l)" -eq 1 ]
    then
        eval $pat '"$@"'
    else
        echo >&2 "tool.bash: error: $pat is not unique!"
        exit 127
    fi
fi

tool.bash.demo.md

tool.bash demo

$ tree ~/.local/bin/ -P "groovy*" -L 1
/home/cschulz/.local/bin/
├── groovy
└── groovyc -> groovy

3 directories, 2 files

$ tree ~/.local/opt -P "groovy*" -L 1
/home/cschulz/.local/opt
├── groovy-2.4.21
└── groovy-3.0.12

$ export GROOVY_VER_DEFAULT=2.4

$ groovy --version
Groovy Version: 2.4.21 JVM: 11.0.16 Vendor: Ubuntu OS: Linux

$ groovyc --version
Groovy compiler version 2.4.21
Copyright 2003-2020 The Apache Software Foundation. https://groovy-lang.org/

$ export GROOVY_VER=3.0

$ groovy --version
Groovy Version: 3.0.12 JVM: 11.0.16 Vendor: Ubuntu OS: Linux

$ groovyc --version
Groovy compiler version 3.0.12
Copyright 2003-2022 The Apache Software Foundation. https://groovy-lang.org/