Editing Newline (section)

=== Conversion between newline formats ===
[[Text editor]]s are often used for converting a text file between different newline formats; most modern editors can read and write files using at least the different ASCII {{mono|CR}}/{{mono|LF}} conventions.

For example, the editor [[Vim (text editor)|Vim]] can make a file compatible with the Windows Notepad text editor. Within vim
<syntaxhighlight lang="vim">
 :set fileformat=dos
 :wq
</syntaxhighlight>
Editors can be unsuitable for converting larger files or bulk conversion of many files. For larger files (on Windows NT) the following command is often used:
<syntaxhighlight lang="doscon">
D:\>TYPE unix_file | FIND /V "" > dos_file
</syntaxhighlight>
Special purpose programs to convert files between different newline conventions include [[unix2dos|{{mono|unix2dos}} and {{mono|dos2unix}}]], {{mono|mac2unix}} and {{mono|unix2mac}}, {{mono|mac2dos}} and {{mono|dos2mac}}, and {{mono|flip}}.<ref>{{cite web |last1=Sapp |first1=Craig Stuart |title=ASCII text converstion between UNIX, Macintosh, MS-DOS |url=http://ccrma-www.stanford.edu/~craig/utility/flip/ |publisher=Center for Computer Research in Music and Acoustics |archive-url=https://web.archive.org/web/20090209015201/http://ccrma-www.stanford.edu/~craig/utility/flip/ |archive-date=9 February 2009}}</ref>
The {{mono|[[tr (Unix)|tr]]}} command is available on virtually every [[Unix-like]] system and can be used to perform arbitrary replacement operations on single characters. A DOS/Windows text file can be converted to Unix format by simply removing all ASCII {{mono|CR}} characters with
 $ [[tr (Unix)|tr]] -d '\r' &lt; ''inputfile'' &gt; ''outputfile''
or, if the text has only {{mono|CR}} newlines, by converting all {{mono|CR}} newlines to {{mono|LF}} with
 $ [[tr (Unix)|tr]] '\r' '\n' &lt; ''inputfile'' &gt; ''outputfile''

The same tasks are sometimes performed with [[awk]], [[sed]], or in [[Perl]] if the platform has a Perl interpreter:
<syntaxhighlight lang="console">
$ awk '{sub("$","\r\n"); printf("%s",$0);}' inputfile > outputfile  # UNIX to DOS  (adding CRs on Linux and BSD based OS that haven't GNU extensions)
$ awk '{gsub("\r",""); print;}' inputfile > outputfile              # DOS to UNIX  (removing CRs on Linux and BSD based OS that haven't GNU extensions)
$ sed -e 's/$/\r/' inputfile > outputfile              # UNIX to DOS  (adding CRs on Linux based OS that use GNU extensions)
$ sed -e 's/\r$//' inputfile > outputfile              # DOS  to UNIX (removing CRs on Linux based OS that use GNU extensions)
$ perl -pe 's/\r?\n|\r/\r\n/g' inputfile > outputfile  # Convert to DOS
$ perl -pe 's/\r?\n|\r/\n/g'   inputfile > outputfile  # Convert to UNIX
$ perl -pe 's/\r?\n|\r/\r/g'   inputfile > outputfile  # Convert to old Mac
</syntaxhighlight>
The {{mono|[[File (command)|file]]}} command can identify the type of line endings:
<syntaxhighlight lang="console">
 $ file myfile.txt
 myfile.txt: ASCII English text, with CRLF line terminators
</syntaxhighlight>
The Unix [[grep#Implementations|egrep]] (extended grep) command can be used to print filenames of Unix or DOS files (assuming Unix and DOS-style files only, no classic Mac OS-style files):
<syntaxhighlight lang="console">
$ egrep -L '\r\n' myfile.txt # show UNIX style file (LF terminated)
$ egrep -l '\r\n' myfile.txt # show DOS style file (CRLF terminated)
</syntaxhighlight>

Other tools permit the user to visualise the EOL characters:
<syntaxhighlight lang="console">
$ od -a myfile.txt
$ cat -e myfile.txt
$ cat -v myfile.txt
$ hexdump -c myfile.txt
</syntaxhighlight>