converting number to bitfield string in bash

Question

What might be the most concise way in bash to convert a number into a bitfield character string like 1101?

In effect I am trying to do the opposite of

echo $[2#1101]

Why: I need to send a parameter to a program that takes bitfields in the form of a full string like "0011010110" but often only need to enable one or few bits as in:

SUPPRESSbits=$[1<<16] runscript.sh  # OR
SUPPRESSbits=$[1<<3 + 1<<9] runscript.sh  # much more readable when I know what bits 3 and 9 toggle in the program

Then runscript.sh then sees in its env a SUPPRESSbits=65536 rather than SUPPRESSbits="1000000000000000" and ends in parse error.

kev · Accepted Answer · 2012-04-18 15:21:38Z

6

The easy way:

$ dc <<<2o123p
1111011

$ bc <<<'obase=2; 123'
1111011

answered Apr 18, 2012 at 15:21

kev

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1 Comment

Marcos Over a year ago

Great, it can hardly get more concise than with dc there. So bash doesn't seem to have number-to-string built in

yazu · Accepted Answer · 2012-04-18 15:19:16Z

1

I doubt about bash but you always can use perl:

a=123; b=$(perl -e 'printf "%b", "'$a'"'); echo $b
1111011

answered Apr 18, 2012 at 15:19

yazu

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