Re: Comparing strings

Thank you for the replies. I did go with the case statement and functions.

On Tuesday, July 13, 2021 at 4:29:33 PM UTC-4, Grant Taylor wrote:
> On 7/13/21 11:46 AM, ELCV wrote: 
> > Hello 
> 
> Hi,
> > I can't get this right. What I have is a script to backup VM 
> > guests. The command is called with an argument, for example: 
> > 
> > /usr/local/bin/vm-backup.sh FOO 
> > 
> > Some of the VMs have two disks and I want to back them both up. Two of 
> > the VMs have vert large data partitions that are backed up separately 
> > and I want to exclude them.
> Okay. That sounds like some VMs can use a default, some need slightly 
> different, and still others need something special.
> > If I do this: 
> > 
> > if [ "$1" != "FOO" ]; 
> > then 
> > echo "I can backup the 2nd volume"; 
> > else 
> > exit; 
> > fi 
> > 
> > It works. But if I add an "or" condition as follows: 
> > 
> > if [ "$1" != "FOO" ] || [ "$1" != "BAR" ] ; 
> > then 
> > echo "I can backup the 2nd volume"; 
> > else 
> > exit; 
> > fi 
> > 
> > It fails.
> ORed negative logic is ... tricksy.
> > I have tried this a number of different ways and I can't get it. Any 
> > guidance is appreciated. Thanks.
> I would be tempted to try a case statement: 
> 
> case ${1} in 
> FOO) 
> # FOO's specific backup. 
> BAR|BOB) 
> # specific backup for BAR and BOB. 
> *) 
> # default backup for all other systems. 
> esac 
> 
> I also find that such a case statement is a lot easier to maintain long 
> term as systems are added / changed / removed. 
> 
> Depending on how the backups work, you might consider breaking out the 
> actual backup actions to their discrete steps and call them as a 
> function. E.g. FOO would call functions 1 and 2, while BAR & BOB call 
> functions 2 and 3, and then everyone else would only call functions 1 
> and 3. Use the case as a method to choosoe which pieces to run and then 
> call the necessary common pieces. 
> 
> 
> 
> -- 
> Grant. . . . 
> unix || die