Subject: Re: bug#12482: Feature Request: support for int, octal, and hex types in seq --format

From: Craig Sanders <[email-masked]>
Date: Sat, 22 Sep 2012 01:10:24 +1000

On Fri, Sep 21, 2012 at 10:19:13AM +0200, Jim Meyering wrote:
> Voelker, Bernhard wrote:
> > Craig Sanders wrote:
> >
> >> seq only supports floating point types like f and g in the --format
> >> string.
> >>
> >> Other types, including i,d,o,u,x,X would also be useful.
> >>
> >> e.g. "seq --format 'prefix%02isuffix' 1 50" to print zero-padded
> >> 1-50 with user-specified prefix and suffix strings.
> >
> > IMO custom format strings for pre- or suffixing are not seq's job.

the printf formats I suggested for seq are not specifically about
prefixing or suffixing, they were just part of an example..

what i requested was non-floating point formats (the suffix and prefix
strings are just a side-benefit of printf) - decimal, octal, and hex
integer printf formats d,o,x, etc. if it supports floating-point, why
not fixed or int?

in fact, why floating-point at all? i can think of hundreds of uses in
a shell script for printf-formatted ints from seq (and some for hex and
even a few for octal), but not a single one for floating point. i'd
use perl or python or something else if i wanted to do floating-point
calculations (perl has a nice Math::BigFloat module and python, of
course, has numpy and scipy).

> I agreed, initially.  The texinfo documentation gives examples
> of how to convert seq output to hexadecimal (%x) using printf:

yes, i know there are numerous ways to post-process seq's output.  I
even included a few in my answer to the stackexchange question i linked
to.

if there's some reason why floating point is possible but
the integer formats are not then fair enough....but it doesn't
make sense to me to arbitrarily declare that floating-point
printf support is OK but not integer.

the examples using printf and xargs and so on are both obvious and
missing the point. this bug report is not about them. it's about seq's
incomplete support for printf.

> (the disadvantage with this approach is that you have to pre-compute
> the width and use that number in the printf format, whereas in Bernie's
> example, that's done automatically by seq -w.  This suggests that seq's
> --equal-width (-w) option *would* be handy in conjunction with the requested
> integer format directives.  Then, we'd get the benefit of -w along with
> the more direct use of a seq format string. )

yes!

> That looks like a bug, but printf is actually required to reject
> those two input strings.  A leading "0" means octal.

yeah, ran into that myself and thought WTF until i realised 'oh yeah. octal'.

>     $ seq 12 | xargs printf 'a-%02x-b\n'

yep, but i already knew that.

i'm not asking for help to solve a problem.  I'm submitting a wishlist
level bug report for a feature enhancement to support more of
printf's formatting capabilities in seq.

craig

-- 
craig sanders <[email-masked]>