Re: Piping tail -f to fold: tail -f log.txt | fold

[Bob Proulx]

Philip Durbin wrote:
> To word wrap the output of a growing log file I tried. . .
> $ tail -f log.txt | fold -s
> . . . and it works fine on NetBSD and Mac OS X, but on the two Linux 
> distributions I tried (Red Hat and SUSE) I get no output.

This topic comes up periodically.  Please see this reference for a
recent more thorough discussion:

  http://lists.gnu.org/archive/html/bug-coreutils/2008-11/msg00134.html

> If not, can anyone please explain the difference in the implementation 
> of fold?

In summary it is all about I/O buffering happening in libc's output
routines.  If the output is not a tty then data is buffered for
performance reasons into larger chunks before writing.

> Can piping tail -f to fold be made to work on Linux the way it works on BSD?

There are various methods posted in the other thread.  I will leave
you to browse them.

Bob