Perl - remove carriage return and append next line

Question

What if I have a record in a otherwise good file that had a carriage return in it.

Ex:

1,2,3,4,5 ^M

,6,7,8,9,10

and I wanted to make it

1,2,3,4,5,6,7,8,9,10

Answer 1

s/[\r\n]//g

Only do this if you want to combine a line with the next.

Answer 2

In general, if you have a string with a stray newline at the end that you want to get rid of, you can use chomp on it (note that you can pass it an lvalue, so wrapping it around an assignment is legal):

my $string = $string2 = "blah\n";
chomp $string;

# this works too:
chomp(my $string3 = $string2);

Note that if the string has a trailing "\r\n", chomp won't take the \r as well, unless you modify $/.

So if all of that is too complicated, and you need to remove all occurrences of \n, \r\n and \r (maybe you're processing lines from a variety of architectures all at once?), you can fall back to good old tr:

$string =~ tr/\r\n//d;

Answer 3

Assuming the carriage return is right before the line feed:

perl -pi.bak -e 's/\r\n//' your_file_name

This will join only lines with a carriage return at the end of the line to the next line.

Answer 4

Say we have a file that contains a ctrl-M (aka \r on some platforms):

$ cat input 
1,2,3
4,5,6
,7,8,9
10,11,12

This is explicit with od:

$ od -c input 
0000000   1   ,   2   ,   3  \n   4   ,   5   ,   6  \r  \n   ,   7   ,
0000020   8   ,   9  \n   1   0   ,   1   1   ,   1   2  \n
0000035

Remove each offending character and join its line with the next by running

$ perl -pe 's/\cM\cJ?//g' input 
1,2,3
4,5,6,7,8,9
10,11,12

or redirect to a new file with

$ perl -pe 's/\cM\cJ?//g' input >updated-input

or overwrite it in place (plus a backup in input.bak) with

$ perl -i.bak -pe 's/\cM\cJ?//g' input

Making the \cJ optional handles the case when a file ends with ctrl-M but not ctrl-J.

Answer 5

Every line is ended with some terminator sequence, either

• CRLF (\r\n = 13, 10) on Windows/DOS
• CR (\n = 10) on Unix
• LF (\r = 13) on MacOS

If some lines are OK, you should say from wich system the file comes or on wich system the perl script is executed, or the risk is to remove every end of line and merge all of your program lines...

As ^M is the LF character, if you see such a character at the end of a line and nothing special on other lines, you are probably using some kind of Unix (Linux ?) and some copy/paste has polluted one line with an additional \r at the end of line.

if this is the case :

perl -pi -e 's/\r\n$//g' filetomodify

will do the trick and merge only the line containing both CR and LF with the next line, leaving the other lines untounhed.