"telnet" command fails with "bad port" when executed in shell script, but works on command prompt

Question

This is probably really simple. I am logging into a remote server using PuTTY and running a telnet 12.34.56.789 22 command to test TCP connections on port 22.

This works fine when I type the command manually, but I have a range of destinations to check and I thought it would be better to use a script for this. I created a very basic shell script which is just a list of the commands I want to run one after another. When I run this script from PuTTY I get an error saying

: bad port

Can anyone explain to me why the command works when I type it manually, but produces an error when I run the script?

Script:

telnet 10.52.33.46 22  
telnet 10.52.33.47 22  
telnet 10.52.33.48 22  
telnet 10.52.33.49 22  
telnet 10.52.33.50 22  
telnet 10.52.33.51 22  
telnet 10.52.33.52 22  
telnet 10.52.33.53 22  
telnet 10.52.33.54 22  
telnet 10.52.33.55 22

Here is a screenshot of the PuTTY window with the error message. I save the above script (159999.sh) onto the host server, then run it from there.

Here is some of the commands running after I type them manually (in this case they are supposed to fail to connect)

added to the original question - added a few line spaces for readability — Gary, Oct 19 '17 at 10:14
*"When I run **these**"* - Do you mean *"When I run **this script**"*? How do you run the script (if you do)? Show us a screenshot. — Martin Prikryl, Oct 19 '17 at 10:22
22 is a port of SSH service. It might be that telnet client on your server doesn’t allow port alterations. — 0andriy, Oct 19 '17 at 10:40
OK, show us screenshot running the commands manually. Also can you upload the script somewhere (zipped) for us to check? — Martin Prikryl, Oct 19 '17 at 10:53
struggling to upload the script, but it is essentially the commands in the question, typed on individual lines (without line spaces) in a .sh file and saved on the host server — Gary, Oct 19 '17 at 11:12

Martin Prikryl · Accepted Answer · 2017-10-19T12:41:30.017

1

Your script file has Windows CR/LF line endings, while *nix systems use LF only.

The additional CR is taken as a part of the telnet command, particularly as a part of the last "port" argument. Hence the "bad port" error.

Make sure you either:

save the script using *nix line endings before uploading or
upload the script using a text mode transfer or
convert the file on the server.

edited Oct 19 '17 at 12:41

answered Oct 19 '17 at 11:39

Martin Prikryl

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"telnet" command fails with "bad port" when executed in shell script, but works on command prompt

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