Pattern: Use of literal carriage return in shell script
Issue: -
The script uses Windows/DOS style \r\n line terminators instead of UNIX style \n terminators. The additional \r aka ^M aka carriage return characters will be treated literally, and results in all sorts strange bugs and messages.
You can verify this with cat -v yourfile and see whether or not each line ends with a ^M. To delete them, open the file in your editor and save the file as "Unix", "UNIX/OSX Format", :set ff=unix or similar if it supports it.
If you don't know how to get your editor to save a file with Unix line terminators, you can use tr:
tr -d '\r' < badscript > goodscript
This will read a script badscript with possible carriage returns, and write goodscript without them.
Example of incorrect code:
$ cat -v somescript
#!/bin/sh^M
echo "Hello World"^MExample of correct code:
$ cat -v somescript
#!/bin/sh
echo "Hello World"