2013-01-19



I received a link via the CCC Ulm mailing list:  [0] The  website
includes  the following code to repeat a string multiple times in
the Unix shell:

     printf "ha"%.0s {1..5}

[1]

If your Shell does not support the ranges, you may use seq(1) (if
you have it):

     printf "ha"%.0s `seq 5`

or:

     printf "ha"%.0s 1 2 3 4 5

(btw: The placement of the quotes might look a bit  strange.   It
would  be more natural to group the whole argument: ``"ha%.0s"''.
But actually, they could be omited completely in this case.)

This, however, was not the interesting part.  I was a bit puzzled
by  the general solution because I am familiar with printf(3) and
treated printf(1) like a standalone implementation of the library
function. Solving the problem this way would not be possible with
printf(3).

POSIX explains the behavior of printf(1):

     The format operand shall be reused as often  as  neces-
     sary to satisfy the argument operands.  [2]

[0]  http://rosettacode.org/wiki/Repeat_a_string
[1]  http://rosettacode.org/wiki/Repeat_a_string#UNIX_Shell
[2]  http://pubs.opengroup.org/onlinepubs/9699919799/utilities/printf.html


http://marmaro.de/lue/        markus schnalke <meillo@marmaro.de>