Unsetting variable doesn't work

Question

I want to parse if the user input is an integer, and force him to do so. First time (iquant) running chkip() works, second time (idays), I immediately get: "Error: Not a number. Please retry." New input works then. I am unsetting ipn before break, so what's the deal?

chkip()
{
    ipn=$1
    while true;
    do
        if [[ "$ipn" =~ ^[0-9]+$ ]] ; then 
            unset ipn
            break
        else 
            echo "Error: Not a number. Please retry"
            read ipn
        fi
    done
}

echo "Please enter the name of the Set:"
read ap
echo "How much keys do you want to create [NUMBER]:"
read iquant
chkip $iquant 
echo "How often do you want to change the Keys? [DAYS] ?:"
read idays
chkip $idayz

You probably want to quote those expansions ("$1", "$iquant", etc), and consider set -u to get an error when you try to use an unset variable. — Toby Speight
– Toby Speight, Commented Nov 9, 2016 at 18:09
Maybe you should also add a return value, because after the correction iquant will contain the old value and ipn will be out of scope. — Ko Cour
– Ko Cour, Commented Nov 9, 2016 at 18:12
Welcome to stackoverflow! +1 for including complete, self-contained source code, expected result and actual result. This makes the question clear, unambiguous and easy to answer and verify. — that other guy
– that other guy, Commented Nov 9, 2016 at 19:24

Ulises André Fierro · Accepted Answer · 2016-11-09 18:06:50Z

3

The problem is that you're reading "idays" but passing "idayz" instead of the former.

read idays
chkip $idayz

Change $idayz to $idays and you'll be on your way.

answered Nov 9, 2016 at 18:06

Ulises André Fierro

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Comments

Toby Speight · Accepted Answer · 2016-11-10 09:27:50Z

1

You have a bigger problem: your function only modifies the variable named ipn, not whatever variable whose value you pass as an argument.

This function takes the name of a variable, and uses indirect parameter expansion to check the value of that variable. The value of var is passed to read as the name of the variable to populate.

chkip () {
  local var=$1
  until [[ ${!var} =~ ^[[:digit:]]$ ]]; then
    read -p "Error: Not a number. Please retry: " "$var"
  done
}

Here, the name, not the value, of the variable is passed as the argument to chkip.

read -p "Please enter the name of the set: " ap
read -p "How many keys do you want to create? [NUMBER]: " iquant
chkip iquant 
read -p "How often do you want to change the keys? [DAYS]: " idays
chkip idays

edited Nov 10, 2016 at 9:27

Toby Speight

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answered Nov 9, 2016 at 19:37

chepner

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