Bash script - How is 6 > 50?

Question

if [[ 6 > 50 ]]; then
    echo "true"
fi

$ bash script.sh

I'm missing something very obvious here. Why is 6 greater than 50 ??

** EDIT **

I'm also try to solve for

if [[ 6.5 > 50 ]]; then
    echo "true"
fi

From man bash: "When used with [[, the < and > operators sort lexicographically using the current locale." — steeldriver, Sep 09 '20 at 01:06

score 3 · Accepted Answer · answered Sep 09 '20 at 01:38

3

If you need to compare floats, the easiest way is to call out to an external tool like awk or bc

a=6.1
b=50
if [[ "$(echo "$a > $b" | bc)" -eq 1 ]]; then echo "a greater than b"; fi

answered Sep 09 '20 at 01:38

glenn jackman

I'm not as familiar with bash scripting (obviously) so I appreciate you answering my "silly" question with a formative and informational answer rather than exercising contempt on me for knowing less than you in this given situation. Cheers @glennJackman – Jacksonkr Sep 09 '20 at 14:03
1

No worries. There are no silly questions, providing you follow a few sensible guidelines. – glenn jackman Sep 09 '20 at 15:42

score 3 · Answer 2 · answered Sep 09 '20 at 02:07

3

If you're comparing integers then use

if [[ 6 -gt 50 ]]; then echo "true"; fi

otherwise since bash cannot handle floating point

if (( $(echo "6.5 > 50" | bc -l) )); then echo "true"; fi

answered Sep 09 '20 at 02:07

boots

score 2 · Answer 3 · answered Sep 09 '20 at 01:18

2

You supplied [[ args ]] which is a conditional expression, when you meant to perform arithmetic evaluation which uses the (( condition )) syntax.

answered Sep 09 '20 at 01:18

chahu418

In certain situations I have a float in there and when I've tried this I get syntax error: invalid arithmetic operator (error token is ".00 > 50 ") – Jacksonkr Sep 09 '20 at 01:21
1

@Jacksonkr Bash does not do floats. A good starting point for questions like these is to consult man bash. – John1024 Sep 09 '20 at 01:21
@John1024 What about like this – Jacksonkr Sep 09 '20 at 01:36

3 Answers3