I wrote this code in bash shell script with error

Question

I wrote this code:

echo -n "Enter a number1  "
echo -n "Enter a number2  "
read R1
read R2

while [ "$R1" < "$R2"]
do 
if [ $((R1 % 2)) -eq 0 ]; then

$R3=$R1

    echo "Number is $R3"
else
    echo "Nothing"
fi

done

I don't understand why it always give me this error bash: 8]: No such file or directory

Your specific error message is caused by the lack of space before the closing ] argument, which would need to be inserted in addition to the fix given in the answers. — chepner
– chepner, Commented Oct 10, 2013 at 11:55

justhalf · Accepted Answer · 2013-10-10 10:08:45Z

1

You should use -lt instead of <.

while [ "$R1" -lt "$R2" ]

< is interpreted as input redirection in bash.

Or you can use double square brackets to interpret those inside as arithmetic operation:

while [[ "$R1" < "$R2" ]]

answered Oct 10, 2013 at 10:08

justhalf

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4 Comments

Haneen Abd-Al-Haleem Over a year ago

thank you it works but I stuck with infinite loop that disappointed me command not found;number =2;

justhalf Over a year ago

What do you want to accomplish? Asking user to input two number everytime?

Haneen Abd-Al-Haleem Over a year ago

am thinking of Write a Bash shell script that reads as arguments two integer parameters (R1, and R2), if R1 < R2, prints all even numbers between R1 and R2. Otherwise prints out nothing, so I do this

P.P Over a year ago

@justhalf I think, you gave the answer first with correct fix+1 ;-)

P.P · Accepted Answer · 2013-10-10 10:35:07Z

1

What happens since < "$R2" is intrepreted as read from "$R2". Since you don't have a file with such a name, it complains.

[ (test command) command doesn't have < operator. You have to use -lt instead:

while [ "$R1" -lt "$R2" ]

There's a POSIX extenstion which supports it with a slash:

while [ "$R1" \< "$R2" ]

If you are using bash you bash then you can also use built-in [[ ..]] which has support for <, > etc.

while [[ "$R1" < "$R2" ]]

7 Comments

Haneen Abd-Al-Haleem Over a year ago

thank you it works but I stuck with infinite loop that disappointed me command not found;number =2

P.P Over a year ago

You don't change neither of R1 and R2. Hence, once it enters the loop, it won't break. Depending on what you wanted to do with the code, you may change R1 or R2 or use a break statement on some condition.

Haneen Abd-Al-Haleem Over a year ago

am thinking of Write a Bash shell script that reads as arguments two integer parameters (R1, and R2), if R1 < R2, prints all even numbers between R1 and R2. Otherwise prints out nothing, so I do this

justhalf Over a year ago

I'll give the honor to you Blue Moon, to solve this problem, rather than competing each other. =)

Haneen Abd-Al-Haleem Over a year ago

should I make R1,R2 initially equal o zero

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