how to use one validation function many times "bash centos"

Question

I want to use only one validation function many times. I tried to make a validation function like beneath. How can I fix my code and use the validation function like this one many times?

#!/bin/bash
digit='^[[:digit:]]+$';
function numberValidate {
    if [[ $1 =~ $digit ]];
       then
          echo "$1 is number. Correct";
       else
          echo “Enter only numbers”;
          numberValidate
    fi
}
printf “Enter the number 1 ”; read n1;
numberValidate $n1
printf “Enter the  number 2”; read n2;
numberValidate $n2

Thanks.

The recursive call to `numberValidate` when there's a problem is probably wrong. The function doesn't get passed any value but it expects one, and it doesn't prompt for a value. You need to think a bit harder about how to get this to work. You'll need to be able to prompt (again) for a number from within the function, and you'll need to be able to get the value out of the function somehow... — Jonathan Leffler, Dec 20 '15 at 02:58
The use of smart quotes here is one thing that's obviously wrong. Was your code copied and pasted from a Microsoft platform? — Charles Duffy, Dec 20 '15 at 15:58
That said, there's no actual **question** in this question -- it's nothing but a dump of code that shows that you already *do* know how to call a function more than once (which is what the title would seem to indicate you to be asking). If you're asking why the code fails in a given way, describe the failure mode and what you intend it to do; see http://stackoverflow.com/help/how-to-ask. — Charles Duffy, Dec 20 '15 at 16:00

score 1 · Answer 1 · answered Dec 20 '15 at 03:35

1

Don't use recursion when a loop will do:

inputNumber () {
    local digit='^[[:digit:]]+$'
    read $n
    until [[ ${!n} =~ $digit ]]; do
        echo "Enter only numbers"
        read $n
    done
}
printf "Enter the number 1 "; inputNumber n1
printf "Enter the number 2 "; inputNumber n2

The preceding moves all the input into the validation function, and takes advantage of the fact that variables set in a function are global by default. The argument to inputNumber is the name of the variable to set.

answered Dec 20 '15 at 03:35

chepner

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1

In this case no difference, but I would suggest `printf "%s" "Enter the number 1 "`. – Walter A Dec 20 '15 at 09:58
1

I tried your code and it didn't work for me. I had to make the following changes: No indirection on n (`read n` and `${n} =~ $digit`) and add the line `printf -v $1 '%s' $n`. What did I miss in your solution? – Walter A Dec 20 '15 at 10:04
Good question; I'm not sure. – chepner Dec 20 '15 at 14:06
I needed to add oneline, just before `read $n`. The line was `n="$1"`. – Walter A Dec 20 '15 at 19:03

score 1 · Answer 2 · edited May 23 '17 at 12:15

inputNumber () {
    local digit='^[[:digit:]]+$'
    outputvar=$1
    shift
    if [[ $# = 0 ]]; then
       read -p "Please enter a number for ${outputvar} "
    else
       read -p "$* " n
    fi
    until [[ "${n}" =~ $digit ]]; do
        read -p "Enter only numbers " n
    done
    printf -v "${outputvar}" '%s' "$n"
}

inputNumber n1 "Enter the number 1"
inputNumber n2 "Enter the number 2"
inputNumber n3
echo "n1=${n1} n2=${n2} n3=${n3}"

Question in a comment: How to reuse these? When you like functions like this one, you can collect them in files and put them in a dedicated directory. Perhaps choose ${HOME}/shlib as a folder and create files like iofunctions, datefunctions, dbfunctions and webfunctions (or io.sh, date.sh, db.sh and web.sh). Next you can source the files with a dot:

$ head -2 ${HOME}/shlib/iofunctions
# This file should be included with ". path/iofunctions"
function inputnumber {

$ cat ${HOME}/bin/roger.sh
#!/bin/bash
# Some settings
shlibpath=/home/roger/shlib
# Include utilities
. "${shlibpath}"/iofunctions
# Let's rock
inputNumber rockcount How many rocks
# call an imaginary function that only accepts y and n
inputyn letsdoit Are you sure

You can put the functions (or source the function files) in your .profile/.bashrc, but that will give problems when you want to start the script in crontab (and you will get used to the functions and forget that inputNumber is not a standard bash function).
Another question is how you can refer to another directory that is on the same level as your script file (not a fixed path). Including ../shlib/iofunctions will fail when you start your script using a path (like bin/roger.sh). A good question with many answers, I can't tell which is the best:
How to set current working directory to the directory of the script?
Getting the source directory of a Bash script from within
Reliable way for a bash script to get the full path to itself?
How to set current working directory to the directory of the script?
how to get script directory in POSIX sh?

To improve this code. this solution works in one file(bash). If y one to work in another file, I have to copy this function. "this function for each file(bash)". — Roger, Dec 20 '15 at 14:11
THE QUESTION IS How I have in one file many functions and from another file only call this file to work. — Roger, Dec 20 '15 at 14:18

how to use one validation function many times "bash centos"

2 Answers2