On Sat, 3 Mar 2012 09:35:36 -0800 (PST)
Rich Shepard <[email protected]> wrote:
> This morning I'm seeing this error when the script looks at
> www.whatismyip.com for the assigned IP address:
>
> /home/rshepard/shell-scripts/ngetip.sh: line 4: [: too many arguments
>
> What is recommended for error checking and graceful recovery in a
> bash shell script like mine? BTW, I can point the browser to that URL
> and it does load so I don't know why the script is retuning this
> error.
First thing I'd do is put quotes around the variables in the test:
if [ "$NEWIP" != "$OLDIP" ]; then
This ensures that both variables are actually strings, which is
all the != operator understands.
Second thing would be to put some rudimentary error checking ahead
of the test, after $NEWIP is set:
if [ -z "$NEWIP" ]; then
echo "FATAL: curl did not return a new IP"
exit 2
fi
Third, run the script with the -x flag:
$ bash -x ngetip.sh
This puts bash in xtrace mode, which makes debugging much easier.
It will let you see what is being returned for $NEWIP. Once you
know that, you can set up your input filtering. Or you could
simply add echo statements in strategic locations. Whatever
works for you.
Hope this helps,
--Dale
--
Q: How many IBM CPUs does it take to execute a job?
A: Four; three to hold it down, and one to rip its head off.
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