rsync - Feb 2014 - /usr/bin/ssh not found when rsync is executed within rsnapshot

Hello,

yesterday i posted this issue on snapshot-discuss at listsourceforge.net
(subject:
wondering why backup wont start), but after reading the FAQ and searching the
bugzilla DB i thought it could help to post here as well.

i have a problem. But let me first describe my setup. i followed this howto:

	http://dev.kprod.net/?q=linux-backup-rsnapshot-no-root

Now there is a backup server rpi-home and a remote host debx40. On both these
computers there is debian jessie (with rsnapshot version 1.3.1) installed, there
is a user backupuser and as far as i can see the remote login with password for
that user works:

backupuser at rpi-home ~ $ ssh debx40 -i ~/.ssh/id_rsa
Linux debx40 3.12-1-486 #1 Debian 3.12.9-1 (2014-02-01) i686
###some greeting lines###
$ whoami
backupuser

here is the result of
grep -v "#" /etc/rsnapshot | grep [a-z]
i.e. the /etc/rsnapshot minus the comments and the empty lines:

config_version	1.2
snapshot_root	/media/extfp/Backup/rsnapshot/test/
no_create_root	1
cmd_cp		/bin/cp
cmd_rm		/bin/rm
cmd_rsync	/usr/bin/rsync
cmd_ssh	/usr/bin/ssh
cmd_logger	/usr/bin/logger
retain		hourly	6
retain		daily	7
retain		weekly	4
verbose		5
loglevel	5
logfile	/var/log/rsnapshot.log
lockfile	/var/run/rsnapshot.pid
rsync_long_args	-ev --rsync-path=/home/backupuser/rsync-wrapper.sh
ssh_args	-i /home/backupuser/.ssh/id_rsa
link_dest	0
rsync_numtries	1
backup	backupuser at debx40:/	debx40/

and this is the content of /home/backupuser/rsync-wrapper.sh on the remote
debx40.

#!/bin/sh

date >> /home/backupuser/backuplog
echo $@ >> /home/backupuser/backuplog
/usr/bin/sudo /usr/bin/rsync "$@";

in the /etc/sudoers there is a line

backupuser ALL=NOPASSWD: /usr/bin/rsync

when i enter e.g. sudo rsnapshot -D hourly on the backup server rpi-home i get
this

require Lchown
Lchown module loaded successfully
Setting locale to POSIX "C"
echo 4702 > /var/run/rsnapshot.pid
mkdir -m 0755 -p /media/extfp/Backup/rsnapshot/test/hourly.0/
/usr/bin/rsync -av -ev --rsync-path=/home/backupuser/rsync-wrapper.sh \
    --rsh="/usr/bin/ssh -i /home/backupuser/.ssh/id_rsa" backupuser at
debx40:/ \
    /media/extfp/Backup/rsnapshot/test/hourly.0/debx40/
rsync: Failed to exec /usr/bin/ssh -i /home/backupuser/.ssh/id_rsa: No such file
or directory (2)
rsync error: error in IPC code (code 14) at pipe.c(85) [Receiver=3.1.0]
rsync: connection unexpectedly closed (0 bytes received so far) [Receiver]
rsync error: error in rsync protocol data stream (code 12) at io.c(226)
[Receiver=3.1.0]
----------------------------------------------------------------------------
rsnapshot encountered an error! The program was invoked with these options:
/usr/bin/rsnapshot -D hourly
----------------------------------------------------------------------------
ERROR: /usr/bin/rsync returned 12 while processing backupuser at debx40:/
/usr/bin/logger -i -p user.err -t rsnapshot /usr/bin/rsnapshot -D hourly: \
    ERROR: /usr/bin/rsync returned 12 while processing backupuser at debx40:/
touch /media/extfp/Backup/rsnapshot/test/hourly.0/
No directory to delete: /media/extfp/Backup/rsnapshot/test/_delete.4702
rm -f /var/run/rsnapshot.pid
/usr/bin/logger -i -p user.err -t rsnapshot /usr/bin/rsnapshot -D hourly: \
    ERROR: /usr/bin/rsnapshot -D hourly: completed, but with some errors

I suppose the important info is in that line

rsync: Failed to exec /usr/bin/ssh -i /home/backupuser/.ssh/id_rsa: No such file
or directory (2)

but surprisingly to me: the Backup starts when i do

sudo /usr/bin/rsync -av -ev --rsync-path=/home/backupuser/rsync-wrapper.sh \
    --rsh="/usr/bin/ssh -i /home/backupuser/.ssh/id_rsa" backupuser at
debx40:/ \
    /media/extfp/Backup/rsnapshot/test/hourly.0/debx40/

, which is the exact same command (copy-pasted from the rsnapshot output) that
caused the error
in the first place. Except the sudo in front of it.

What could be the reason? How could i debug this?

--
kind Regards
Lorenz from Greifswald

On Mon 10 Feb 2014, Lorenz wrote:
> grep -v "#" /etc/rsnapshot | grep [a-z]
> i.e. the /etc/rsnapshot minus the comments and the empty lines:
I'd recommend using 'grep .' to find non-empty lines... shorter and
more
accurate :-)
> rsync_long_args	-ev --rsync-path=/home/backupuser/rsync-wrapper.sh
-e is the short version of --rsh so I don't know what you're trying to
do here... use the 'v' command instead of (the default) ssh? Probably
not.
> /usr/bin/rsync -av -ev --rsync-path=/home/backupuser/rsync-wrapper.sh \
>     --rsh="/usr/bin/ssh -i /home/backupuser/.ssh/id_rsa"
backupuser at debx40:/ \
>     /media/extfp/Backup/rsnapshot/test/hourly.0/debx40/
> rsync: Failed to exec /usr/bin/ssh -i /home/backupuser/.ssh/id_rsa: No such
file or directory (2)
Besides the extraneous -e option this should work.
The error message is a bit misleading though.

Make sure that there are no "wrong" whitespace characters in there.
I've fallen into the trap of copy&pasting commands / configs from
websites and having them fail mysteriously, until I noticed I could not
left-shift those lines in vim with << . Those leading spaces were not
spaces but "no-break spaces", hex value 0x80.

So check your config / scripts with "LANG=C cat -v /etc/rsnapshot"
etc.
> What could be the reason? How could i debug this?
I often use "strace -f -e execve command ..." and / or
"strace -f -e execve command ..." in such cases to see what
it is really trying to run.

Paul

On 10/02/14 05:38, Lorenz wrote:
 > i have a problem. But let me first describe my setup. [...rsnapshot 
configuration...]
 > cmd_ssh    /usr/bin/ssh
 > ssh_args    -i /home/backupuser/.ssh/id_rsa
 > rsync: Failed to exec /usr/bin/ssh -i /home/backupuser/.ssh/id_rsa: 
No such file or directory (2)

There's a bug in some versions of rsnapshot that causes it to try and 
execute cmd_ssh + ssh_args as a single command. The workaround is either 
to put as much of ssh_args as possible into $HOME/.ssh/config for the 
specific target host, or to create a /usr/local/bin/ssh-for-rsnapshot 
type script that incorporates the call to ssh with the relevant arguments.

Chris

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