Question

I would like to modify the value to an element of an array and I don’t know the syntax to do it

for i in `seq 0 8`;
do
    if [ ${config[$i]} = "value1" ]
        then config[$i] = "value2"    #<- This line
    fi
done

Answer 1

Technically, the only thing broken there is the whitespace. Don’t put spaces around your operators in shell syntax:

config[$i]="value2"

However, there are lots of other little things you may want to think about. For example, if an element of config can contain whitespace, the test can break. Use quotes or the [[ test keyword to avoid that.

… if [[ ${config[$i]} = "value1" ]]
    then config[$i]="value2" …

seq is a nonstandard external executable. You’d be better off using the builtin iteration syntax. Furthermore, assuming the iteration happens over all the elements in config, you probably just want to do:

for ((i=0; i<${#config[@]}; i++));
do
    if [[ ${config[$i]} = "value1" ]]
        then config[$i]="value2"
    fi
done