while (sysread(INPUT,$buf,104)) {
  print OUT $buf."\n";
}
[download]

Or do you intend to break the lines in sensible places, as long as no line is longer than 105 characters? For that you would need to scan through the buffer for the sensible place in which to put the newline.

(1) might be more efficient to set $/ to '.' if the file is large, and then read into an array line by line
(2) use file locking and don't close the file in between, if that's necessary, e.g. if more than one process might open the file

if you're having problems with one of the steps you're welcome to add specific questions.
something to read: perlopentut, perlre, flock

perl -pi.bak -e 'BEGIN{$/=\104;}$_ .= qq/\n/;' filename.txt

HTH

If you set $\ to "\n", you don't even need the second statement — at least, not for every loop. Using the -l command line switch, you don't even need any code.

perl -pi.bak -e 'BEGIN{$/=\104;$\=qq/\n/}' filename.txt
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or

perl -lpi.bak -e 'BEGIN{$/=\104}' filename.txt
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For Windows, you'll have to adapt the quote characters around the code.

I wouldn't have immediately guessed that the -l switch would work because the POD for perlrun states that if a value is omitted from the -l switch, it sets $\ equal to $/. Since we're changing the value of $/ in the BEGIN{} block, and since the BEGIN{} block executes at least before the -p switch, I figured that using -l would set $\ to \104. Obviously that's not the case and I was just overthinking it.

Good call bart. Great one-liner!




Dave

Thanks Bart! The one liner did work marvel for me.

 
#!/usr/bin/perl 

while (read DATA, $buf, 27) {
   print $buf, "\n";
}

__DATA__
This is test line number 1.This is test line number 2.This is test lin
+e number 3.This is test line number 4.This is test line number 5.This
+ is test line number 6.
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Hi,

Even though the file isn't supposed to have new lines in it, I would still check for the newline character and strip it if it is present. Why? You might run across a file (I'm assuming you're going to run this on multiple files or more than just once) that contains a new line character and you might end up with lines of 105 characters, then 5 character line, then 105 characters. It would break your requirement of 105 character lines.

hope this helps

Jason L. Froebe