[TUHS] basic tools / Universal Unix
steffen at sdaoden.eu
Wed Oct 18 06:22:27 AEST 2017
Tony Finch <dot at dotat.at> wrote:
|Dan Cross <crossd at gmail.com> wrote:
|> This is an aside, but I must admit -- with a sense of mild shame --
|> that the '-v' option to cat is one that I use with some regularity.
|4.4BSD has the vis(1) and unvis(1) utilities which are more principled
|implementations of this feature (with corresponding section 3 functions).
|It's slightly annoying being on Linux without vis and having to resort to
|`cat -v` like some kind of savage.
Stop! The inner circle of Unix/POSIX standard developers have
(again) shown great wisdom and have put it down black on white:
Historical versions of the cat utility include the *e, *t, and
*v, options which permit the ends of lines, <tab> characters,
and invisible characters, respectively, to be rendered visible
in the output. The standard developers omitted these options
because they provide too fine a degree of control over what is
made visible, and similar output can be obtained using a command
sed *n l pathname
The latter also has the advantage that its output is
unambiguous, whereas the output of historical cat *etv is not.
But mind you, in preparation of this email i found a bug in
Busybox sed(1) which simply echoes nothing for the above.
|Der Kragenbaer, The moon bear,
|der holt sich munter he cheerfully and one by one
|einen nach dem anderen runter wa.ks himself off
|(By Robert Gernhardt)
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