Bash Script- Issue with variables and | bc

Question

So I have a variable that I want to compare with another number in an if statement.

b=8.25
if [ $(echo "$b < 10" | bc) -ne 0 ]; then
echo "hey"
fi

I get the following error

(standard_in) 1: syntax error

I know the issue is having the b variable inside, how can I make it so that I can maintain it in there?

Please help

It works for me in Bash. What shell are you using?

codeforester
– codeforester

2018-05-05 19:48:24 +00:00
Commented May 5, 2018 at 19:48 — codeforester
– codeforester, Commented May 5, 2018 at 19:48
You can try b=$'8.25\r';[ ${b%.*} -lt 10 ] && echo "hey"

ctac_
– ctac_

2018-05-05 20:23:44 +00:00
Commented May 5, 2018 at 20:23 — ctac_
– ctac_, Commented May 5, 2018 at 20:23

glenn jackman · Accepted Answer · 2018-05-05 19:48:30Z

2

Your script file probably has DOS-style CRLF line endings:

$ b=8.25
$ if [ $(echo "$b < 10" | bc) -ne 0 ]; then
> echo "hey"
> fi
hey

$ b=$'8.25\r'
$ if [ $(echo "$b < 10" | bc) -ne 0 ]; then
> echo "hey"
> fi
(standard_in) 1: illegal character: ^M
bash: [: -ne: unary operator expected

Run dos2unix on your script file.

answered May 5, 2018 at 19:48

glenn jackman

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2 Comments

tbot Over a year ago

I am using mobaXterm at my school and I don't have permission to run dos2unix, what else can I do?

glenn jackman Over a year ago

Those 2 facts have nothing to do with each other. Use sed 's/\r$//'

user5063151 · Accepted Answer · 2018-05-05 19:47:51Z

0

Store the comparison in a variable separateley

b=8.25

# Capture output outside the if
comparison=$(echo  "$b < 10" | bc)

# Use the output in the if
if [ $comparison -ne 0 ]; then

    echo "hey"
fi

answered May 5, 2018 at 19:47

user5063151

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