Deleting/Removing Control M characters in Linux

Control-M is a character found at the end of a line usually in files in linux/unix. We need to delete these characters before processing this file.

To put a control m character, please Press Cntrl followed by V and M(Control-V+Control-M) and not as Shift-6-M.

Viewing the control M characters we can use below commands:

1) cat -v filename
2) vi -b filename

To Remove Control M characters we can use below methods:

1. dos2unix The simplest of all is using the dos2unix command.

dos2unix filename

Note: I have seen occurences where the this command dont remove all Control-M characters so I prefer below menthod

2. tr Command

$ tr -d '^M' <filename

To store output after deleting the Control-M we can use below
tr -d '^M' <filename > newfile

We can also use below 

$ tr -d "\015" <filename >newfile

3. sed command

$ sed -e 's/^M//g' filename

To remove and save changes to file use below

$ sed -i 's/^M//g' filename

4. vi Editor in the escape mode type below:
5. awk command

The 1 is used to print the lines.
$ awk 'sub(/^M/,"");1' filename