How to show zero before decimal point in bc?

Question

echo "scale=3;1/8" | bc

shows .125 on the screen. How to show 0.125 if the output result is less than one?

Crosslink: Same question on StackOverflow: Bash script: specify bc output number format - Stack Overflow — user202729, Nov 10, 2023 at 11:35

cuonglm · Accepted Answer · 2015-04-22 14:52:21Z

18

bc can not output zero before decimal point, you can use printf:

$ printf '%.3f\n' "$(echo "scale=3;1/8" | bc)"
0.125

answered Apr 22, 2015 at 14:48

cuonglm

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score 2 · Accepted Answer · 2015-04-22 14:52:04Z

2

You can pipe into awk

echo "scale=3;1/8" | bc | awk '{printf "%.3f\n", $0}'

or you could just use awk for it all

awk '{printf "%.3f\n", 1/8}' <<< ""

0.125

answered Apr 22, 2015 at 14:43

user78605

1

Why should we do <<< ""?
– Kevin Dong
Apr 22, 2015 at 14:47
1

@KevinDongNaiJia awk requires an input file to work, this creates and empty here string. So basically pretends there is an empty file at the end, otherwise awk will read from stdin.More info here
– user78605
Apr 22, 2015 at 14:49
1

@JID: Not all shell supported here string, you need to specify it for others viewers. Using BEGIN block prevent you from that trouble and it's portable.
– cuonglm
Apr 22, 2015 at 14:59

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Coder · Accepted Answer · 2021-06-17 16:00:27Z

1

Bettering @cuonglm's answer:

a=10.543; b=`printf '%.6f' "$(echo "$a/100" | bc -l)"`; echo $b;

Use "bc -l" to use math library.

answered Jun 17, 2021 at 16:00

Coder

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3 Answers 3