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.

Your question tags, title and shebang says `bash`, but your script is `csh`. `bash` and `csh` are two different languages. Which language do you intend to write the script in? — that other guy, Nov 04 '16 at 01:06
I intend to write in `csh` but am running it from the `bash` shell — Young Emil, Nov 04 '16 at 01:13

score 2 · Accepted Answer · edited Nov 10 '16 at 16:11

2

The shebang must be set to the shell that should interpret the script. It doesn't matter which shell you run the script from. The only thing that matters is the language the script is written in.

Your script is written in csh, and must therefore have the shebang #!/bin/csh. This is true even if you want to run it from bash. Also, you were missing a space in your at-sign-ment:

$ cat me.csh
#!/bin/csh
set i = 1
echo it starts

while ($i <= 5)
        echo i is $i
        @ i = $i + 1
end

Output:

$ ./me.csh
it starts
i is 1
i is 2
i is 3
i is 4
i is 5

edited Nov 10 '16 at 16:11

Young Emil

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answered Nov 04 '16 at 01:29

that other guy

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Thanks but am getting this error : `bash: ./me.csh: /bin/csh: bad interpreter: No such file or directory` . And my using Kali linux and I don't know if it doesn't have `csh`. – Young Emil Nov 04 '16 at 01:36
If it doesn't have csh, you either have to install csh or rewrite your script into a language you *do* have support for. – that other guy Nov 04 '16 at 02:09
I installed `csh` and now its working with `#!/bin/csh`. Thanks for your ideas. – Young Emil Nov 04 '16 at 02:46

paulsm4 · Answer 2 · 2016-11-04T01:11:44.253

0

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

edited Nov 04 '16 at 01:11

answered Nov 04 '16 at 00:59

paulsm4

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Am sorry but maybe I wasn't more specific. I have edited my question. – Young Emil Nov 04 '16 at 01:20

score -1 · Answer 3 · answered Dec 12 '21 at 09:49

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

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

3 Answers3