--- /dev/null
+## 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. As long as master ssh connection is live, slave
+can use it. Disconnecting master all future attempts to connect
+from the script will fail.
+
+At the end of this document there is information for some possible ways
+how master ssh connection can be done.
+
+## The script
+
+Write the following code to a file, for example `remote-notmuch.sh`.
+
+ #!/bin/bash
+
+ # http://notmuchmail.org/remoteusage/124/
+
+ set -eu
+ # To trace execution, uncomment next line.
+ #BASH_XTRACEFD=6; exec 6>>remote-errors; echo -- >&6; set -x
+
+ 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 -q $SSH_CONTROL_ARGS 0.1 $notmuch $ARGS
+ then exit 0
+ else ev=$?
+ 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'*'--batch'*) while read line; do echo 1; done; 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' "$0"` for help."
+ #EOF
+
+Note the `0.1` in ssh command line. It is used to avoid any opportunistic
+behaviour ssh might do; for example if control socket is not alive ssh
+would attempt to do it's own ssh connection to remote ssh server. As
+address `0.1` is invalid this attempt will fail early.
+
+## Test
+
+Easiest way to test this script is to run the pre-made ssh connection
+using the following command line:
+
+ ssh -M -S '~'/.ssh/master-user@host:22 [user@]remotehost sleep 600
+
+(replace `[user@]remotehost` with your login info). Doing this the
+above wrapper script can be run unmodified. After the above command has
+been run on **one terminal**, enter `chmod +x remote-notmuch.sh` in
+**another terminal** and then test the script with
+
+ ./remote-notmuch.sh help
+
+Note that the '~' in the ssh command line above is inside single quotes
+for a reason. In this case shell never expand it to `$HOME` -- ssh does
+it by not reading `$HOME` but checking the real user home directory
+from `/etc/passwd`. For security purposes this is just how it should
+be.
+
+## Tune
+
+The path `'~'/.ssh/master-user@host:22` might look too generic to be
+used as is as the control socket after initial testing (but it can
+be used). It is presented as a template for what could be configured
+to `$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.
+
+
+## Creating master connection
+
+As mentioned so many times, using this solution requires one pre-made
+ssh connection in "master" mode. The simplest way is to dedicate one
+terminal for the connection with shell access to the remote machine:
+
+ ssh -M -S '~'/.ssh/master-user@host:22 [user@]remotehost
+
+One possibility is to have this dedicated terminal in a way that the
+connection has (for example 1 hour) timeout:
+
+ ssh -M -S '~'/.ssh/master-user@host:22 [user@]remotehost sleep 3600
+
+The above holds the terminal. The next alternative puts the command in
+background:
+
+ ssh -f -M -S '~'/.ssh/master-user@host:22 [user@]remotehost sleep 3600
+
+If you don't want this to timeout so soon, use a longer sleep, like 99999999
+(8 9:s, 1157 days, a bit more than 3 years).
+
+A more "exotic" solution would be to make a shell script running on remote
+machine, checking/inotifying when new mail arrives. When mail arrives it
+could send message back to local host, where a graphical client (to be written)
+pops up on display providing info about received mail (and exiting this
+graphical client connection to remote host is terminated).
+
+## Troubleshooting
+
+If you experience strange output when using from emacs first attempt to just
+run
+
+ ./remote-notmuch.sh help
+
+from command line and observe output. If it looks as it should be next uncomment
+the line
+
+ #BASH_XTRACEFD=6; exec 6>>remote-errors; echo -- >&6; set -x
+
+in `./remote-notmuch.sh` and attempt to use it from emacs again -- and then
+examine the contents of `remote-errors` in the working directory emacs was
+started.
projects / obsolete / notmuch-wiki / blobdiff