While loop in shell script not working in the linux bash shell

Question

Am kind of newbie in writing shell scripts in linux. Its a csh script but am running it in the bash shell that why I used #!/bin/bash instead of #!/bin/csh.

  1 #!/bin/bash
  2 set i = 1
  3 echo it starts
  4 
  5 while ($i <= 5)
  6         echo i is $i
  7         @ i= $i +1
  8 end

**Note: ** The numbers are just to number the lines.

The above code gives me the output with error:

it starts
./me.csh: line 9: syntax error: unexpected end of file

I can't figure out what is wrong even though it echos it starts and there is no line number 9 as specified in the error.

Answer 1

Try this:

#!/bin/bash
echo it starts

i=1
while [ $i -le 5 ]; do
  echo i is $i
  i=$(( i+1 ))
done

Sample output:

it starts
i is 1
i is 2
i is 3
i is 4
i is 5

Here is a great reference:

BASH Programming - Introduction HOW-TO

Answer 2

you should use Visual Studio Code with some extensions to check bash script syntax. I use Vscode in Window 10 WSL2 to run bash script.

change (...) to ((...)) to fix error syntax:

#!/bin/bash
a=5

while ((a > 0)); do
    echo "a = $a"
    a=$((a - 1))
done