Assuming you've started with something like this

folder1=10 folder2=4 folder3=7 

You can write it out with a command such as this

set | grep -E '^folder[0-9]+=' > counter.txt 

To read it back in again you can simply source the file

source counter.txt 

If you have a shell that handles arrays (bash, zsh) you can index the set of folders to an arbitrarily large number

folder[1]=10 folder[2]=4 folder[3]=7 

And write this one variable array out with

set | grep '^folder=' > counter.txt 

Read it back in using source, as above.

For arrays you would reference them like this echo "${folder[1]}" or foreach f "${folder[@]}"; do ... done.

Assuming you've started with something like this

folder1=10 folder2=4 folder3=7 

You can write it out with a command such as this

set | grep -E '^folder[0-9]+=' > counter.txt 

To read it back in again you can simply source the file

source counter.txt 

If you have a shell that handles arrays (bash, zsh) you can index the set of folders to an arbitrarily large number

folder[1]=10 folder[2]=4 folder[3]=7 

And write this one variable array out with

set | grep '^folder=' > counter.txt 

Read it back in using source, as above.

For arrays you would reference them like this echo "${folder[1]}" or foreach f "${folder[@]}"; do ... done. Or even this if your index values are in strict ascending order from 1:

i=1 while [[ $i -le ${#folder[*]} ]] do echo "$i => ${folder[$i]}" ((i++)) done