On Thu, May 07, 2009 at 10:12:59PM -0700, Jason Todd Slack-Moehrle wrote: > > I need to write a script that I will manually start (or a cron job in > future) but I need it to do a number of things in order one after > another. How do i do that so everything gets dont as the steps depend > on each other. > > My questions: > 1. How do I execute each statement and make sure subsequent statements > are not executed until the previous is done?
Use the '&&' (logical "and") operator to pipeline the commands:
cd /foo/bar && tar cvf /path/to/tarball
This will only execute the "tar" command if the previous "cd"
succeeded.
> 2. How do I error check so if a step fails the script stops?
Most commands set a return status upon completion or
error; this value is returned to the shell in the "$?"
variable.
You could write the above as something like:
cd /foo/bar
if [ $? -ne 0 ]
then
echo "cd failed ($?) - bailing out"
exit 1
fi
tar cvf /path/to/tarball
if [ $? -ne 0 ]
then
echo "tar failed ($?) - bailing out"
exit 2
fi
This checks the return status of each command, checks to see if
it's not 0 (0 is "success") and if it is not alerts the user
and exits with it's own error status.
> 3. Since I run an SMTP Server on this box can I e-mail myself from
> bash the nightly results?
Yep. "echo error message" | mail -s "script failure" u...@dom.ain
Will mail the specified user a message containing "error
message" with a subject of "script failure".
> 4. when I want to run the scp to send over the file to another machine
> for safety, how can I have it know the password to the machine I am
> scp'ing to?
You do this with public key authentication. "man ssh-keygen"
for information on how to create a keypair.
> My mind is going crazy sort of with the things that I could do to
> protect myself in case of a system failure and making restoring easier.
We've all been there.
> Can anyone provide insight for me?
Test everything. On regular schedules. If you have the
hardware available simulate a disaster condition and restore
your backups to identical hardware to prove (to yourself and
to management) that your disaster recovery steps actually
do work.
John
--
"I'm sorry but our engineers do not have phones."
As stated by a Network Solutions Customer Service representative when asked to
be put through to an engineer.
"My other computer is your windows box."
Ralf Hildebrandt
<sxem> trying to play sturgeon while it's under attack is apparently not fun.
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