Libfmt is a port of Plan 9's formatted print library.
As a base it provides all the syntax of ANSI printf
but adds the ability for client programs to install
new print verbs.  One such print verb (installed by
default) is %r, which prints the system error string.
Instead of perror("foo"), you can write fprint(2, "foo: %r\n"). 
This is especially nice when you write verbs to format
the data structures used by your particular program.

WWW: http://pdos.lcs.mit.edu/~rsc/software/#libfmt
http://plan9.bell-labs.com/magic/man2html/2/print

Russ Cox
rsc@post.harvard.edu

Maintainer: Markus Friedl <markus@openbsd.org>

WWW: http://pdos.lcs.mit.edu/~rsc/software/
