## Remoteusage without password-free login requirement

This is alternative to [[remoteusage|remoteusage]] where password-free
login is not a requirement. See [[remoteusage|remoteusage]] page for
other requirements and general information.

This solution uses one pre-made ssh connection where the client is put
into "master" mode (-M) for connection sharing. The wrapper script then
uses the control socket created by this pre-made ssh connection for
its own connection.

Write the following code to a file, for example `remote-notmuch.sh`.
There is just one line to that normally needs configuration:

        readonly SSH_CONTROL_SOCK='~'/.ssh/master-user@host:22

the options howto are presented after the script.

## The script

        #!/bin/bash

        # http://notmuchmail.org/remoteusage/aboriginal/

        set -eu

        readonly SSH_CONTROL_SOCK='~'/.ssh/master-user@host:22

        readonly notmuch=notmuch

        printf -v ARGS '%q ' "$@" # bash feature

        readonly SSH_CONTROL_ARGS='-oControlMaster=no -S '$SSH_CONTROL_SOCK

        if ssh $SSH_CONTROL_ARGS 0.1 $notmuch $ARGS 2>>/dev/null
        then exit 0
        else ev=$?
        fi

        # continuing here in case ssh exited with nonzero value.

        case $* in
         'config get user.primary_email') echo 'nobody@nowhere.invalid'; exit 0 ;;
         'config get user.name') echo 'nobody'; exit 0 ;;
         'count'*) echo 1; exit 0 ;;
         'search-tags'*) echo 'errors'; exit 0 ;;
         'search'*'--output=tags'*) echo 'errors'; exit 0 ;;
        esac

        if ssh $SSH_CONTROL_ARGS -O check 0.1
        then
         echo ' Control socket is alive but something failed during data transmission.'
         exit $ev
        fi

        echo " See`sed '1d;2d;s/.//;q' "$0"` for help."

## Test

Easiest way to test this script is to run the pre-made ssh connection
using the following command line:

        ssh -M -S '~'/.ssh/master-user@host:22 [user@]remotehost

(replace `[user@]remotehost` with your login info). Doing this the
above script can be run unmodified. After the above command has been
run on one terminal, enter `chmod +x remote-notmuch.sh` in another
terminal and then test the script with `./remote-notmuch.sh help`

Note that the '~' is inside single quotes for a reason. In this
case shell never expand it to `$HOME` -- ssh does it by not reading
`$HOME` but checking the real user home directory from `/etc/passewd`.
For security purposes this is just how it should be.

## Tunkkaa

The path `'~'/.ssh/master-user@host:22` might look too generic to be
used as is as the control socket after initial testing (but it can
be used). It is presented as a template for what could be configured
to `$HOME/.ssh/config`. For example:

        Host *
            ControlPath ~/.ssh/master-%h@%p:%r

is a good entry to be written in `$HOME/.ssh/config`;
[[remoteusage|remoteusage]] uses the same. Now, let's say you'd
make your pre-made ssh connection with command

        ssh -M alice@example.org

After configuring
`readonly SSH_CONTROL_SOCK='~'/.ssh/master-alice@example.org:22`
to the `./remote-notmuch.sh` wrapper script testing with
`./remote-notmuch.sh help` should work fine.

## Configure Emacs on the client computer ##

See the section *Configure Emacs on the client computer* in
[[remoteusage|remoteusage]] how to do this. The instructions are the same.

## Fun

Original [BSD Licence](http://en.wikipedia.org/wiki/BSD_licenses)
is 4-clause license.
When 3 rd. clause was removed, the new license was not original anymore.
Similarly, the requirement for this version are the same as in
[[remoteusage|remoteusage]] page except the 3 rd. requirement
(password-free login) is not effective here.