Environment variables

    CALCPATH

        A :-separated list of directories used to search for
        resource filenames (*.cal files) that do not begin with:

                /       ./      ../     ~

        If this variable does not exist, or if this
        variable is an empty string, a compiled value
        is used.  Typically compiled in value is:

                    .:./cal:~/cal:${CALC_SHAREDIR}:${CUSTOMCALDIR}

        which is usually:

                    .:./cal:~/cal:/usr/share/calc:/usr/share/calc/custom

        This value is used by the READ command.  It is an error
        if no such readable file is found.

        The CALCBINDINGS file searches the CALCPATH as well.

    CALCRC

        On startup (unless -h or -q was given on the command
        line), calc searches for files along the :-separated
        $CALCRC environment variable.

        If this variable does not exist, or if this
        variable is an empty string, a compiled value
        is used.  Typically compiled in value is:

                    ${CALC_SHAREDIR}/startup:~/.calcrc:./.calcinit

        which is usually:

                    /usr/share/calc/startup:~/.calcrc:./.calcinit

        Missing files along the $CALCRC path are silently ignored.

    CALCBINDINGS

        On startup (unless -h or -q was given on the command
        line), calc reads key bindings from the filename specified
        in the $CALCRC environment variable.  These key bindings
        are used for command line editing and the command history.

        If this variable does not exist, a compiled value is used.
        Typically compiled in value is:

                    bindings

        The bindings file is searched along the CALCPATH.  Unlike
        the READ command, a .cal extension is not added.

        If the file could not be opened, or if standard input is not
        a terminal, then calc will still run, but fancy command line
        editing is disabled.

        NOTE: If calc was compiled with GNU-readline support, the
              CALCBINDINGS facility is ignored and the standard
              readline mechanisms (see readline(3)) are used.

    HOME

        This value is taken to be the home directory of the
        current user.  It is used when files begin with '~/'.

        If this variable does not exist, or if this
        variable is an empty string, the home directory password
        entry of the current user is used.  If that information
        is not available, '.' is used.

    PAGER

        When invoking help, this environment variable is used
        to display a help file.

        If this variable does not exist, or if this
        variable is an empty string, a compiled value
        is used.  Typically compiled in value is something
        such as 'more', 'less', 'pg' or 'cat'.

    SHELL

        When a !-command is used, the program indicated by
        this environment variable is used.

        If this variable does not exist, or if this
        variable is an empty string, a compiled value
        is used.  Typically compiled in value is something
        such as 'sh' is used.

    CALCHISTFILE

        This value is taken to be the calc history file.

        If this variable does not exist, or if this
        variable is an empty string, then ~/.calc_history
        is used.

     CALCHELP

        Location of the calc help directory.

        If this variable does not exist, or if this
        variable is an empty string, then ${HELPDIR}

     CALCCUSTOMHELP

        Location of the calc custom help directory.

        If this variable does not exist, or if this
        variable is an empty string, then ${CUSTOMHELPDIR}
        is used.

In versions prior to v3, you may adhere to the XDG Base Directory
specification by setting up your environment variables as such:

        export CALCRC="${XDG_CONFIG_HOME:-$HOME/.config}/calc/calcrc"
        export CALCPATH=".:${XDG_DATA_HOME:-$HOME/.local/share}/calc:${XDG_CONFIG_HOME:-$HOME/.config}/calc:/usr/share/calc:/usr/share/calc/custom"
        export CALCHISTFILE="${XDG_STATE_HOME:-$HOME/.local/state}/calc/history"

Note that calc won't create the directory tree to $CALCHISTFILE,
you'll need to run:

        mkdir -p $(dirname $CALCHISTFILE)

in order to have the history mechanism if you choose a path to a file
that doesn't exist.

## Copyright (C) 1999,2021  Landon Curt Noll
##
## Calc is open software; you can redistribute it and/or modify it under
## the terms of the version 2.1 of the GNU Lesser General Public License
## as published by the Free Software Foundation.
##
## Calc 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 Lesser General
## Public License for more details.
##
## A copy of version 2.1 of the GNU Lesser General Public License is
## distributed with calc under the filename COPYING-LGPL.  You should have
## received a copy with calc; if not, write to Free Software Foundation, Inc.
## 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
##
## Under source code control:   1991/07/23 05:47:25
## File existed as early as:    1991
##
## chongo <was here> /\oo/\     http://www.isthe.com/chongo/
## Share and enjoy!  :-)        http://www.isthe.com/chongo/tech/comp/calc/
