BASH check if argv is a number between 0 and 100

Question

My curent script

checkargv='^[0-9]+$'
if ! [[ $1 =~ $checkargv ]]
        then
        echo "[!] How many times? $0 [number]" >&2
        exit 1
fi

for (( i=1;i<=$1;i++ ))
do
        x=$[($RANDOM % 100) + 1]
        ./script.sh $x
done

my argv $1 accept right now any number from 0 to does't matter, how can I make the argv accept numbers only from 0 to 100

`[[ ! "$1" =~ ^[0-9]+$ ]] || [[ "$1" -lt 1 ]] || [[ "$1" -gt 100 ]] && { echo invalid ; exit 1; }` — steve, Aug 02 '18 at 17:58

score 2 · Accepted Answer · edited Aug 02 '18 at 19:39

if [ "$1" -lt 1 ] || [ "$1" -gt 100 ]; then
    echo 'error (out of range)' >&2
    exit 1
fi

This assumes that the thing in $1 is actually an integer. You may verify this beforehand with

case "$1" in
    ("" | *[!0-9]*)
        echo 'error (not a positive decimal integer number)' >&2
        exit 1
esac

This will trigger the exit if $1 contains anything other than decimal digits or is empty.

Combining these:

case "$1" in
    ("" | *[!0-9]*)
        echo 'error (not a positive decimal integer number)' >&2
        exit 1
        ;;
    *)
        if [ "$1" -lt 1 ] || [ "$1" -gt 100 ]; then
            echo 'error (out of range)' >&2
            exit 1
        fi
esac

But doing one after the other may look nicer:

case "$1" in
    ("" | *[!0-9]*)
        echo 'error (not a positive decimal integer number)' >&2
        exit 1
esac

if [ "$1" -lt 1 ] || [ "$1" -gt 100 ]; then
    echo 'error (out of range)' >&2
    exit 1
fi

Beware that [ arithmetic operators always consider numbers as decimal even if they start with 0, while the shell's arithmetic expansions in POSIX shells would consider numbers starting with 0 as octal (0100 is 100 for [, but 64 for $((...))).

I forgot to specify that integer must not be 0 as well. so between 1 and 100 — John Doe, Aug 02 '18 at 17:31

score 0 · Answer 2 · answered Aug 02 '18 at 16:39

0

Use arithmetic instead of regex:

if ! (( num >= 0 && num <= 100 ))

(This assumes num is numeric. If you also need to check to make sure $num is numeric, then use the regex as well.)

answered Aug 02 '18 at 16:39

L. Scott Johnson

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BASH check if argv is a number between 0 and 100

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