bashshellvariablesincrementreturn-code

UNIX shell: increment a variable with value of last returned exit code

Let's say I have a counter initialised by counter=0

Now I want to run a command and increment the value of counter by its returned exit code.

In a natural language I want to do counter = $counter + $?

I am trying stuff like counter=$((counter+$((?)))); but with no success. What is the correct way to do it in a single line?

Solution

  • With bash I suggest:

    counter=$(($counter + $?))

    This is also possible:

    counter=$((counter + $?))

    Or:

    declare -i counter=0     # set integer attribute
<your command>
counter=counter+$?

    Or:

    declare -i counter=0
<your command>
counter=+$?