dos2unix and unix2dos commands

Sometimes, you will need to move files between windows and unix systems. Window files use the same format as Dos, where the end of line is signified by two characters, Carriage Return or CR or \r followed by Line Feed or LF or \n.

Unix files, on the other hand, use only Line Feed (\n).

unix2dos is a tool to convert line breaks in a text file from Unix format (Line feed) to DOS format (carriage return + Line feed) and vice versa.

◈ dos2unix command : converts a DOS text file to UNIX format.
◈ Unix2dos command : converts a Unix text file to DOS format

Example

Task : Create a file in DOS or in notepad with following contents
hello everybody
welcome to unix
unix is easy

now copy this file in unix /home/lpi directory

$od –bc myfile.txt
0000000 150 145 154 154 157 040 145 166 145 162 171 142 157 144 171 015
          h   e   l   l   o       e   v   e   r   y   b   o   d   y  \r
0000020 012 167 145 154 143 157 155 145 040 164 157 040 165 156 151 170
         \n   w   e   l   c   o   m   e       t   o       u   n   i   x
0000040 015 012 165 156 151 170 040 151 163 040 145 141 163 171 015 012
         \r  \n   u   n   i   x       i   s       e   a   s   y  \r  \n
0000060

The CR-LF combination is represented by the octal values 015-012 and the escape sequence \r\n.

Note: The above output shows that this is a DOS format file.
Now convert DOS file to UNIX format by using dos2unix command

$dos2unix myfile.txt
$od –bc myfile.txt

Conversion of this file to UNIX is just a simple matter of removing the \r.
We can also convert UNIX file to DOS format by using unixsdos command

$unix2dos myfile.txt
$od –bc myfile.txt

After Conversion of this file to DOS, \r is added in DOS file.