Substitution within string command

Shell Programming and Scripting
1

I have the following code:

 strfuture=abcdefghi
ver=${strfuture:${count}:1}
          mj7777_ver=${ver} start_mj7777_iteration
          let count=count+1

When it is executed I get bad substitution. The same if I use

 ver=${strfuture:$count:1}
          mj7777_ver=${ver} start_mj7777_iteration

How would I do the above, please?
I am trying to do ${strfuture:1:1} ... then ${strfuture:2:1} i.e. indexed string within a loop so I do not have to write it out fully.

Is it possible?

2

Which shell are you using?

3

Hi Subbeh,
Bash shell I believe

4

I don't know exactly what you're trying to do, but the variable substitution should work in bash. You could alternatively try using something like this to loop through all characters in the string:

while test -n "$strfuture" ; do
        c=${strfuture:0:1}
        echo $c
        strfuture=${strfuture:1}
done
5

Hi Subbeh,
I am trying to change

while test $count -le ${CURRENTRUNSCTRL}
      do
          if [ "$count" = 1 ]
          then mj7777_ver='1' start_mj7777_iteration
          fi
          if [ "$count" = 2 ]
          then mj7777_ver='2' start_mj7777_iteration
          fi
          if [ "$count" = 3 ]
          then mj7777_ver='3' start_mj7777_iteration
          fi
          if [ "$count" = 4 ]
          then mj7777_ver='4' start_mj7777_iteration
          fi
          if [ "$count" = 5 ]
          then mj7777_ver='5' start_mj7777_iteration
          fi
          if [ "$count" = 6 ]
          then mj7777_ver='6' start_mj7777_iteration
          fi
          if [ "$count" = 7 ]
          then mj7777_ver='7' start_mj7777_iteration
          fi
          if [ "$count" = 8 ]
          then mj7777_ver='8' start_mj7777_iteration
          fi
          if [ "$count" = 9 ]
          then mj7777_ver='9' start_mj7777_iteration
          fi
          let count=count+1
       done

to this

strcurrent=123456789
      count=1
      while test $count -le ${CURRENTRUNSCTRL}
      do
          ver=${strcurrent:${count}:1}
          mj7777_ver=${ver} start_mj7777_iteration
          let count=count+1
       done

so it is fewer lines and easier to read or add further threads

Thanks for your suggestion though as I will see if I can use it somehow

6

Wouldn't it be easier to use a simple for loop in this case?

for i in {1..9} ; do
        mj7777_ver="$i" start_mj7777_iteration
done
7

Thanks Subbeh,
I will need to try as sometimes I need to do fewer than 9 iterations and other times the ver is a character rather than a number but if I can get my head around how to control it, it may work