linked-install.sh

#!/usr/bin/env bash


## Find true directory script resides in, true name, and true path
__SOURCE__="${BASH_SOURCE[0]}"
while [[ -h "${__SOURCE__}" ]]; do
    __SOURCE__="$(find "${__SOURCE__}" -type l -ls | sed -n 's@^.* -> \(.*\)@\1@p')"
done
__DIR__="$(cd -P "$(dirname "${__SOURCE__}")" && pwd)"
__DIR_NAME__="${__DIR__##*/}"
__NAME__="${__SOURCE__##*/}"
__PATH__="${__DIR__}/${__NAME__}"
__AUTHOR__='S0AndS0'
__DESCRIPTION__='Symbolically links project script to $PATH accessible directory'


__license__(){
    _year="$(date +'%Y')"
    cat <<EOF
${__DESCRIPTION__}
Copyright (C) ${_year:-2020} ${__AUTHOR__:-"S0AndS0"}

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published
by the Free Software Foundation, version 3 of the License.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program.  If not, see <https://www.gnu.org/licenses/>.
EOF
}


__usage__() {
    local _message="${1}"
    cat <<EOF
${__DESCRIPTION__}


--help      -h

    Prints this message and exists


--license   -l

    Prints license and exits


--verbose   -v

    Prints messages about skipped actions


## Example usage


    ./linked-install.sh


Above command will link...
    ${_script_source}

... to...
    ${_script_destination}
EOF

  (("${#_message}")) && {
    printf >&2 '\n## Error: %s\n' "${_message}"
  }
}


## Defaults
_script_source="${__DIR__}/script-apt-get"
_script_destination="/usr/local/sbin/script-apt-get"


(("${#@}")) && {
  case "${@}" in
    '-h'|'--help'|'help')
      __usage__
      exit 0
    ;;
    '-l'|'--license'|'license')
      __license__
      exit 0
    ;;
    '-v'|'--verbose'|'verbose')
      _verbose=1
    ;;
    *)
      __usage__ "Unrecognized argument(s): ${@}"
      exit 1
    ;;
  esac
}


[[ -f "${_script_source}" ]] || {
  printf >&2 'Cannot locate script source -> %s\n' "${_script_source}"
}


[[ -L "${_script_destination}" ]] && {
  printf >&2 'Error: script destination already exists -> %s\n' "${_script_destination}"
  exit 1
}


((_verbose)) && {
  ln -vs "${_script_source}" "${_script_destination}"
} || {
  ln -s "${_script_source}" "${_script_destination}"
}