Converting DOS/UNIX and vice-versa

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There are several utility software to convert text files from UNIX or Linux to DOS operating systems and vice-versa; however, it always helps to know the manual conversion. In shell programming languages like UNIX or Linux the text files conclude with a new line operator"\n" also known as the line feed and its ASCII code is 0A. A DOS Text file concludes a line by the carriage return or the entry key "\r": its ASCII code is 0D. The lines in the DOS end with CRLF or with "\r\n". To convert this DOS text into UNIX or Linux erase the "\r"; you can also use ASCII codes if you are using GNU-sed version. From UNIX to DOS you may add the "\r" or else use GNU-sed notations symbolically, using the ASCII codes.


Though there are (dos2unix and unix2dos) utility programs capable of performing this task, here is a simple tip on how to manually make these features.

Conversion DOS to UNIX / UNIX to DOS

The text files under Unix end their line with the symbol "\n" (called Line Feed and noted LF, ASCII code = 0A).

Text files under DOS by a "line", end their line with the symbol "\r"(called Carriage Return and noted CR, ASCII 0D).
Thus, every line in a DOS file ends with a CRLF sequence, or \r\n.

Conversion from DOS to UNIX

Simply delete the "\r" (carriage return) at the end of the line.
The "\ r" is symbolically represented by "^M", which is obtained by the following sequence of keys "CTRL-V" + "CTRL-M".

sed 's/^M$//' file


With the GNU-sed(gsed 3.02.80) version, we can use the ASCII notation:

sed 's/\x0D$//' file

Conversion from UNIX to DOS

Just do the opposite of the previous command, namely (the "^M" being entered in the same way (CTRL-V + CTRL-M)):

sed 's/$/^M/' file


With the GNU-sed(gsed 3.02.80) version, we can use the symbolic notation "\r":

sed 's/$/\r/' file
Jean-François Pillou

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