[SOLVED] shell script wrapper for automating rsync

someshpr · 06-01-2010, 09:07 PM

Hi,
I wanted to write a shell script wrapper for automatically syncing some folders across machines. The machines are spread over two sub-domains in the parent domain (grp.vpncc.org and hpc.vpncc.org). I have set up public and private keys over the machines so that I can rsync without password. I have three machines archean, jurassic and silurian under grp.vpncc.org which uses a central nfs mounted home directory (/nfs/cretaceous/home/). From these three machines I usually would like to run this syncing. The fourth machine of my interest is cluster.hpc.vpncc.org, but this is I have checked individual rsync commands and that works fine. But when I try to use rsync via the script (autosync.sh):

Code:

#!/bin/bash

arg=$1
usr="somesh@$2"
src=$3
dest=$4

host=`hostname`

case $host in
        archean.grp.vpncc.org)
                key="\"ssh -i /home/somesh/.keys/archean_rsa\""
                ;;
        silurian.grp.vpncc.org)
                key="\"ssh -i /home/somesh/.keys/silurian_rsa\""
                ;;
	jurassic.grp.vpncc.org)
		key="\"ssh -i /home/somesh/.keys/jurassic_rsa\""
		;;
	*)
          	echo "Non Destination:" $host
		;;
esac

echo $arg
echo $key
echo $usr
echo $src
echo $dest

f="rsync $arg -e $key $usr:$src $dest"
echo $f
rsync $arg -e $key $usr:$src $dest

I get this error:

Code:

somesh@archean temporst$ ./autosync.sh -avz cluster.hpc.vpncc.org /gpfs/home/somesh/myScripts/ .
-avz
"ssh -i /home/somesh/.keys/archean_rsa"
somesh@cluster.hpc.vpncc.org
/gpfs/home/somesh/myScripts/
.
rsync -avz -e "ssh -i /home/somesh/.keys/archean_rsa" somesh@cluster.hpc.vpncc.org:/gpfs/home/somesh/myScripts/ .
building file list ... rsync: link_stat "/home/somesh/.keys/archean_rsa"" failed: No such file or directory (2)
rsync: link_stat "/nfs/cretaceous/home/somesh/myScripts/temporst/somesh@cluster.hpc.vpncc.org:/gpfs/home/somesh/myScripts/." failed: No such file or directory (2)
done

sent 29 bytes  received 20 bytes  98.00 bytes/sec
total size is 0  speedup is 0.00
rsync error: some files could not be transferred (code 23) at main.c(892) [sender=2.6.8]

But when I use the command

Code:

rsync -avz -e "ssh -i /home/somesh/.keys/archean_rsa" somesh@cluster.hpc.vpncc.org:/gpfs/home/somesh/myScripts/ .

it works fine.

What am I doing wrong?

All the systems run RHEL 5 or CentOS 5.

TIA,

timmeke · 06-02-2010, 03:54 AM

The "" in the link_stat error seems to suggest it's a quoting issue - it seems to look for a file called
/home/somesh/.keys/archean_rsa"

Since the key value does not need any expansion, using single quotes could help.
Something like:

Code:

key='ssh -i /home/somesh/.keys/archean_rsa'
...
rsync $arg -e "$key" $usr:$src $dest

The script should also exit when an inappropriate host is specified (* case), as it would
still continue with an empty $key as it is now.

someshpr · 06-02-2010, 08:10 AM

Thanks timmeke! That works!

Yes, I should add an exit statement for * case.

BTW, what are the differences of "" and ''?

timmeke · 06-03-2010, 01:31 AM

Plz read the section on quoting in

Code:

man bash

In practice, single quotes are for literal strings - no expansion of e.g. variables is done.
So '$key' would match the exact string $key, without substituting the value of the variable.

Double quotes do expand.