The values don't get updated in my custom command prompt when I hit enter

Question

I am trying to make a custom command prompt that looks like this: [][][][]$, where the [] can be filled with custom information. For example, if I write in the console . file.sh 0 2 "date -R" then the command prompt looks like this [Sat, 29 Aug 2020 11:02:40 +0200][][][]$ the 0 stands for position, and 2 stands for the type of the value (1 is string, 2 is command which is in this example, and 3 is a csv file) Basically, I want my command prompt to be dynamic, so every time I hit enter the values should be updated (not all values have to be updated, for example string stays the same all the time, or a csv column.) So when I hit enter I want my prompt go from [Sat, 29 Aug 2020 11:02:40 +0200][][][]$ to [Sat, 29 Aug 2020 11:02:45 +0200][][][]$ for example. Here is my full code:

#!/bin/bash

updatedata() {



v=$(awk -v strSearch="$1" '
BEGIN{
    FS=";"
}
{
    gsub(/\r/,"")
    for(i=1;i<=NF;i++){
        if($i==strSearch){ print i
            exit
        }
    }
}
' data.csv)

sum=0
for x in `cut -f $v -d ';' data.csv`
do
    x="${x/$'\r'/}"
    let sum=$sum+$x
done

if [ $pos -eq 0 ]
then
    v0=$sum
elif [ $pos -eq 1 ]
then
    v1=$sum
elif [ $pos -eq 2 ]
then
    v2=$sum
elif [ $pos -eq 3 ]
then
    v3=$sum
fi




         
}
           

       
while [ "$#" -gt 0 ]; do
    pos=$1
    typevar=$2
    stringvar=$3
    case $pos in
      0) v0=$3 ;;
      1) v1=$3 ;;
      2) v2=$3 ;;
      3) v3=$3 ;;
      *) echo "One of the values has invalid position entered, try again"
     
    esac
    case $typevar in
      1) if [  $pos -eq 0 ]
        then
            if [ "$stringvar" != "null" ]
            then
                v0=$stringvar
            else
                v0=""
            fi
        elif [ $pos -eq 1 ]
        then
            if [ "$stringvar" != "null" ]
            then
                v1=$stringvar
            else
                v1=""
            fi
        elif [ $pos -eq 2 ]
        then
            if [ "$stringvar" != "null" ]
            then
                v2=$stringvar
            else
                v2=""
            fi
        elif [ $pos -eq 3 ]
        then
            if [ "$stringvar" != "null" ]
            then
                v3=$stringvar
            else
                v3=""
            fi
        fi ;;
           
       
      2) if [ $pos -eq 0 ]
        then
            v0=`eval $3`
        elif [ $pos -eq 1 ]
        then
            v1=`eval $3`
        elif [ $pos -eq 2 ]
        then
            v2=`eval $3`
        elif [ $pos -eq 3 ]
        then
            v3=`eval $3`
        fi ;;
      3) updatedata $3 ;;
      *) echo "Invalid type of variable, try again"
     
     
     
    esac
    shift
    shift
    shift
   
done

export PS1="[$v0][$v1][$v2][$v3]$"

I tried using export for the PS1, didn't work. I also tried using single quoted for the PS1 like this: export PS1='[$v0][$v1][$v2][$v3]$' and that didn't work either. I also tried to do this: export PS1='[$(v0)][$(v1)][$(v2)][$(v3)]$' and that didn't work either. I don't know what to do!

example of CSV file:

Date_of_report;Municipality_code;Municipality_name;Province;Total_reported;Hospital_admission;Deceased
2020-03-13 10:00:00;GM0003;Appingedam;Groningen;0;0;0
2020-03-13 10:00:00;GM0010;Delfzijl;Groningen;0;0;0
2020-03-13 10:00:00;GM0014;Groningen;Groningen;3;0;0
2020-03-13 10:00:00;GM0024;Loppersum;Groningen;0;0;0
2020-03-13 10:00:00;GM0034;Almere;Flevoland;1;1;0
2020-03-13 10:00:00;GM0037;Stadskanaal;Groningen;0;0;0
2020-03-13 10:00:00;GM0047;Veendam;Groningen;0;0;0
2020-03-13 10:00:00;GM0050;Zeewolde;Flevoland;1;0;0
2020-03-13 10:00:00;GM0059;Achtkarspelen;Friesland;0;0;0
2020-03-13 10:00:00;GM0060;Ameland;Friesland;0;0;0
2020-03-13 10:00:00;GM0072;Harlingen;Friesland;0;0;0
2020-03-13 10:00:00;GM0074;Heerenveen;Friesland;0;0;0

Answer 1

Your script currently only updates the prompt when it is explicitly sourced. If you want it to run every time the prompt refreshes, I think you need to use PROMPT_COMMAND.

Try the following modified script. This will call the function set_prompt to update the prompt every time. I've also exported the commands to generate the text so that they can be run again to update when you get a new prompt. Using your example command of . file.sh 0 2 "date -R", I can then see the date update when I press enter.

#!/bin/bash

updatedata() {

v=$(awk -v strSearch="$1" '
BEGIN{
    FS=";"
}
{
    gsub(/\r/,"")
    for(i=1;i<=NF;i++){
        if($i==strSearch){ print i
            exit
        }
    }
}
' data.csv)

sum=0
for x in `cut -f $v -d ';' data.csv`
do
    x="${x/$'\r'/}"
    let sum=$sum+$x
done

echo $sum

}


while [ "$#" -gt 0 ]; do
    pos=$1
    typevar=$2
    stringvar=$3
    case $pos in
      0) v0=$3 ;;
      1) v1=$3 ;;
      2) v2=$3 ;;
      3) v3=$3 ;;
      *) echo "One of the values has invalid position entered, try again"

    esac
    case $typevar in
      1) if [  $pos -eq 0 ]
        then
            if [ "$stringvar" != "null" ]
            then
                export PROMPT0="echo $stringvar"
            else
                export PROMPT0=""
            fi
        elif [ $pos -eq 1 ]
        then
            if [ "$stringvar" != "null" ]
            then
                export PROMPT1="echo $stringvar"
            else
                export PROMPT1=""
            fi
        elif [ $pos -eq 2 ]
        then
            if [ "$stringvar" != "null" ]
            then
                export PROMPT2="echo $stringvar"
            else
                export PROMPT2=""
            fi
        elif [ $pos -eq 3 ]
        then
            if [ "$stringvar" != "null" ]
            then
                export PROMPT3="echo $stringvar"
            else
                export PROMPT3=""
            fi
        fi ;;


      2) if [ $pos -eq 0 ]
        then
            export PROMPT0="exec $3"
        elif [ $pos -eq 1 ]
        then
            export PROMPT1="exec $3"
        elif [ $pos -eq 2 ]
        then
            export PROMPT2="exec $3"
        elif [ $pos -eq 3 ]
        then
            export PROMPT3="exec $3"
        fi ;;

      3) if [ $pos -eq 0 ]
        then
            export PROMPT0="updatedata $3"
        elif [ $pos -eq 1 ]
        then
            export PROMPT1="updatedata $3"
        elif [ $pos -eq 2 ]
        then
            export PROMPT2="updatedata $3"
        elif [ $pos -eq 3 ]
        then
            export PROMPT3="updatedata $3"
        fi ;;

      *) echo "Invalid type of variable, try again"


    esac
    shift
    shift
    shift

done

function set_prompt() {
    v0=$($PROMPT0)
    v1=$($PROMPT1)
    v2=$($PROMPT2)
    v3=$($PROMPT3)

    export PS1="[$v0][$v1][$v2][$v3]$"
}

export PROMPT_COMMAND=set_prompt