Re: AT_DATA and AS_ECHO_N

[Paolo Bonzini]

Thanks, I'm committing it with this additional rewording..

> +While @command{printf} is not available on all systems, it is safer and
> +easier to use than @command{echo}.
> +Thus, new applications which are not aiming at portability should use
> address@hidden instead of @command{echo}.
> +When portability is important, M4sh provides the @code{AS_ECHO} and
> address@hidden macros, which choose between @samp{echo -n} on
> +implementations where that works, @command{printf} if it is available,
> +or other creative tricks in order to work around the above problems.

While @command{printf} is not a builtin on all systems, it is safer and
easier to use than @command{echo}.  Thus, scripts where portability is 
not a major concern should use @command{printf '%s\n'} instead of 
@command{echo}, and @command{printf %s} instead of @command{echo -n}. 
For portable shell scripts it is suggested to use M4sh and its 
@code{AS_ECHO} and @code{AS_ECHO_N} macros, which choose between various 
implementations: @samp{echo} or @samp{print} where that works, 
@command{printf} if it is available, or other creative tricks in order 
to work around the above problems.

> address@hidden is not available on all systems.

@command{printf} is not always a builtin; if not, every invocation would 
cause a fork and the consequent speed penalty.