bash case staement 2

[roycrom]

Hello all,

I doubt this is possible, but here goes:

In PHP, you can do the following

switch(true) {
   case ( "$TEST1" == "0" AND "$TEST2" == "0" ):
        echo "both 0";
        break;

    case ( "$TEST1" == "0" AND "$TEST2" == "1" ):
        echo "different";
        break;
}

basically allowing you to test two variables in a case statement.

I really don't think this is possible but my script is getting unwieldy with massive "if - elseif" blocks.

Any idea one way or another if its possible to do similar in bash?

Thanks for your help

------------------------------------------
Somethings come from nothing, nothing seems to come from somethings - SFA - Guerilla

roycrom

 

[PHV]

In your shell man page take a look at case ... esac

Hope This Helps, PH.
FAQ219-2884
FAQ181-2886

 

[columb]

The nearest I can think of is

while :
do
  if [ $TEST1 -eq 0 -a $TEST2 -eq 0 ]
  then
    echo both zero
    break
  fi
  if [ $TEST1 -eq 1 -a $TEST2 -eq 0 ]
  then
    echo different
    break
  fi
  echo no test passed
  break
done

Which can be written more concisly as

while :
do
  [ $TEST1 -eq 0 -a $TEST2 -eq 0 ] && { echo the same; break; }
  [ $TEST1 -eq 0 -a $TEST2 -eq 1 ] && { echo dfferent; break; }
  echo no test passed
  break
done

Ceci n'est pas une signature
Columb Healy

 

[roycrom]

PHV - thanks, but I already did that and it looks like its not possible, my request here was just a last resort after multiple web searches too. Thanks for your reply though.

Columb - thats a nice hint, thanks, if nothing else I can test that and if it works as I need then at least it will make my code more readable, I'm cleaning up stuff I did years ago, I can't juggle all those if, elsifs in my head anymore, in fact I can only just make sense of what I wrote and we have a new starter who is going to look at them and I feel cruel letting him try to work out WTH is going on!


------------------------------------------
Somethings come from nothing, nothing seems to come from somethings - SFA - Guerilla

roycrom

 

[Annihilannic]

Another idea:

case $TEST1$TEST2 in
        00) echo both zero ;;
        10) echo one zero ;;
        *)  echo something else ;;
esac

Annihilannic.

 

[roycrom]

Ahhh, thats interesting Annihiannic,
maybe more readable if we did it like

case ${TEST1}XX${TEST2}XX${TEST3} in
    0XX0XX0) echo "All zero" ;;
    0XX0XX1) echo "yada yada yada" ;;
    ........
    1XX1XX1) echo "All ones" ;;
    *) echo "something is wrong!" ;;
esac

As you may have noticed I put three variables in here,
I actually have four variables that I'm testing, so there are A LOT of permutations, maybe a nested case statement would be better. What do you think?
I've never had any formal training and just bodged together most of my scripts as they were needed.

------------------------------------------
Somethings come from nothing, nothing seems to come from somethings - SFA - Guerilla

roycrom

 

[roycrom]

Actually better with underscores instead of the double X

case ${TEST1}_${TEST2}_${TEST3} in
0_0_0) echo "ALL Zeroes" ;;
.............
esac

------------------------------------------
Somethings come from nothing, nothing seems to come from somethings - SFA - Guerilla

roycrom

 

[columb]

I have only one issue with Annihilannic's rather clever solution and that is maintainability. When, in a couple of years time, you have to revisit the code and you see the line

 0_1_0_0) do_something;;

it's going to be hard to work out exatly how the 0_1_0_0 string was obtained. it won't be too bad if the individual case statements are short but it you're having to refer back a hundred lines or so to remind yourself exactly what the conditions were...

So make sure you comment well.

Ceci n'est pas une signature
Columb Healy