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.
+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.
-Write the following code to a file, for example `remote-notmuch.sh`.
-There is just one line to that normally needs configuration:
+## The script
- readonly SSH_CONTROL_SOCK='~'/.ssh/master-user@host:22
+Write the following code to a file, for example `remote-notmuch.sh`.
-the options howto are presented after the script.
+ #!/bin/bash
-## The script
+ # http://notmuchmail.org/remoteusage/aboriginal/
- #!/bin/bash
+ set -eu
+ # To trace execution, outcomment next line. Note that emacs input may ...
+ #exec 2>>remote-errors; echo -- >&2; set -x # ... change (no stderr).
- # http://notmuchmail.org/remoteusage/aboriginal/
+ readonly SSH_CONTROL_SOCK='~'/.ssh/master-user@host:22
- set -eu
+ readonly notmuch=notmuch
- readonly SSH_CONTROL_SOCK='~'/.ssh/master-user@host:22
+ printf -v ARGS '%q ' "$@" # bash feature
- readonly notmuch=notmuch
+ readonly SSH_CONTROL_ARGS='-oControlMaster=no -S '$SSH_CONTROL_SOCK
- printf -v ARGS '%q ' "$@" # bash feature
+ if ssh -q $SSH_CONTROL_ARGS 0.1 $notmuch $ARGS
+ then exit 0
+ else ev=$?
+ fi
- readonly SSH_CONTROL_ARGS='-oControlMaster=no -S '$SSH_CONTROL_SOCK
+ # continuing here in case ssh exited with nonzero value.
- if ssh $SSH_CONTROL_ARGS 0.1 $notmuch $ARGS 2>>/dev/null
- then exit 0
- else ev=$?
- fi
+ 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
- # continuing here in case ssh exited with nonzero value.
+ if ssh $SSH_CONTROL_ARGS -O check 0.1
+ then
+ echo ' Control socket is alive but something failed during data transmission.'
+ exit $ev
+ fi
- 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
+ echo " See`sed '1d;2d;s/.//;q' "$0"` for help."
- 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' "$0"` for help."
+Note the `0.1` in ssh command line. It is used to avoid any opportunistic
+behaviour ssh might do; for example if control socket is not alive ssh
+would attempt to do it's own ssh connection to remote ssh server. As
+address `0.1` is invalid this attempt will fail early.
## Test
Note that the '~' is inside single quotes for a reason. In this
case shell never expand it to `$HOME` -- ssh does it by not reading
-`$HOME` but checking the real user home directory from `/etc/passewd`.
+`$HOME` but checking the real user home directory from `/etc/passwd`.
For security purposes this is just how it should be.
-## Tunkkaa
+## 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
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.