Backup Script

rajwinder · #1 (**permalink**) 11-23-2008

I wrote a simple backup script but want to do some error handling ..

So this script do all the stuff and finally creates one tar file on remote machine using :

Code:

/usr/local/bin/tar cvzf - -T $ListFileName | /usr/local/bin/ssh trusteduser@192.168.32.2 "cat > /appl/test/$BTYPE-$APP-`date +%Y%m%d`.tar.gz"

trusted user can login without password due to ssh trust .. It works fine but here is the issue .. What if something happened to ssh trust the bash script will prompt for password and that is it

.

Now i thought of couple of things :

1. Check for ssh trust before executing tar by :

/usr/local/bin/ssh trusteduser@192.168.32.2 'exit'

but again it will not work if it ask for password

2. execute the above command in a kind of subshell and wait for output till 5- 10 seconds and then exit .. not sure how to do this. Wait command will not kill it if didnt fininshed before n secods.

Please suggest

otheus · #2 (**permalink**) 02-03-2009

The last week of November can be a little tricky to get any American to answer questions. We're all sleeping after eating whole Turkeys.

Try this:

Code:

ssh -o Numberofpasswordprompts=0 trusteduser@192.168.32.2 true

If SSH needs to prompt for a password, it will see that it can prompt 0 times, and try another authentication method. If none can be found, it will exit with 255 and the message:

Code:

Permission denied (publickey,gssapi-with-mic,password).

The "true" runs the command "true" on the remote host, guaranteeing a zero result. So you can just do this:

Code:

if ssh -o Numberofpasswordprompts=0 trusteduser@192.168.32.2 true; then
   true;
else
   echo >&2 Cannot reach remote server without login prompt.
   exit 1
fi

<your tar|ssh command>

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