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2011-03-12 - Confoo 2011 presentation
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2011-01-04 - Moderation now required for new commands
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Commands tagged bc from sorted by
Terminal - Commands tagged bc - 19 results
function b58encode () { local b58_lookup_table=({1..9} {A..H} {J..N} {P..Z} {a..k} {m..z}); bc<<<"obase=58;ibase=16;${1^^}"|(read -a s; for b58_index in "${s[@]}" ; do printf %s ${b58_lookup_table[ 10#"$b58_index" ]}; done); }

A bitcoin "brainwallet" is a secret passphrase you carry in your brain.

The Bitcoin Brainwallet Private Key Base58 Encoder is the third of three functions needed to calculate a bitcoin PRIVATE key from your "brainwallet" passphrase.

This base58 encoder uses the obase parameter of the amazing bc utility to convert from ASCII-hex to base58. Tech note: bc inserts line continuation backslashes, but the "read s" command automatically strips them out.

I hope that one day base58 will, like base64, be added to the amazing openssl utility.

alias ?=concalc
2014-01-02 01:46:44
User: boynux
Functions: alias

Same functionality without using bash functions.

echo 0$(awk '/Pss/ {printf "+"$2}' /proc/$PID/smaps)|bc
2013-09-26 18:20:22
User: atoponce
Functions: awk echo
Tags: Linux awk echo bc proc

The "proportional set size" is probably the closest representation of how much active memory a process is using in the Linux virtual memory stack. This number should also closely represent the %mem found in ps(1), htop(1), and other utilities.

=() { echo $(($*)); }
2013-05-03 04:27:07
User: xlz
Functions: echo

POSIX compliant arithmetic evaluation.

= 10*2+3

hex() { bc <<< "obase=16; $1"; }
2011-12-09 13:57:05
User: bjomape
Functions: bc
Tags: bash hex bc numbers

Use the standard calculator bc to convert decimals to hex

seq 1 2 99999999 | sed 's!^!4/!' | paste -sd-+ | bc -l
2011-02-09 23:36:07
User: flatcap
Functions: bc paste sed seq
Tags: sed seq bc paste math

Calculate pi from the infinite series 4/1 - 4/3 + 4/5 - 4/7 + ...

This expansion was formulated by Gottfried Leibniz: http://en.wikipedia.org/wiki/Leibniz_formula_for_pi

I helped rubenmoran create the sum of a sequence of numbers and he replied with a command for the sequence: 1 + 2 -3 + 4 ...

This set me thinking. Transcendental numbers!

seq provides the odd numbers 1, 3, 5

sed turns them into 4/1 4/3 4/5

paste inserts - and +

bc -l does the calculation

Note: 100 million iterations takes quite a while. 1 billion and I run out of memory.

echo "e("{1..8}");" | bc -l
seq 8 | awk '{print "e(" $0 ")" }' | bc -l
2010-08-14 02:52:39
User: polar
Functions: awk bc seq
Tags: awk seq bc

If you want a sequence that can be plotted, do:

seq 8 | awk '{print "e(" $0 ")" }' | bc -l | awk '{print NR " " $0}'

Other bc functions include s (sine), c (cosine), l (log) and j (bessel). See the man page for details.

echo "($(date +%s)-$(date +%s -d "march 1"))/86400"|bc
2010-07-22 19:44:50
User: nickwe
Functions: echo
Tags: echo bc date

Exactly the same number of characters, exactly the same results, but with bc

echo 'obase=16; C+F' | bc
2010-04-14 20:35:31
User: rkulla
Functions: echo
Tags: hex bc math asm

To do hex to binary: echo 'ibase=16; obase=2; 16*16' | bc # prints: 111100100

To do 16*16 from decimal to hex: echo 'ibase=10; obase=16; 16*16' | bc # prints: 100

You get the idea... Alternatively, run bc in interactive mode (see man page)

year=2010; math=`echo "$year%4" | bc`; [ ! -z $year ] && [ $math -eq 0 ] && echo "$year is leap year!" || echo "$year isn't leap year";
echo $((3.0/5.0))
echo "5 k 3 5 / p" | dc
2009-09-03 00:21:54
User: xamaco
Functions: echo

using bc is for sissies. dc is much better :-D

Polish notation will rule the world...

bc -l <<< s(3/5)
2009-09-02 15:41:39
User: akg240
Functions: bc

-l auto-selects many more digits (but you can round/truncate in your head, right) plus it loads a few math functions like sin().

echo "scale=4; 3 / 5" | bc
2009-08-21 21:51:46
User: foob4r
Functions: echo

allows you to use floating point operations in shell scripts

echo $( du -sm /var/log/* | cut -f 1 ) | sed 's/ /+/g'
2009-07-31 21:42:53
User: flux
Functions: cut du echo sed
Tags: echo bc

When you've got a list of numbers each on its row, the ECHO command puts them on a simple line, separated by space. You can then substitute the spaces with an operator. Finally, pipe it to the BC program.

? () { echo "$*" | bc -l; }
2009-06-28 20:15:30
User: fizz
Functions: bc echo

defines a handy function for quick calculations from cli.

once defined:

? 10*2+3
echo "obase=2; 27" | bc -l
2009-03-25 09:54:50
User: polar
Functions: bc echo
Tags: bc

Easily convert numbers to their representations in different bases. Passing

"ibase=16; obase=8; F2A"

to bc will convert F2A (3882 in decimal) from Hex to Octal, and so on.

echo "$math_expr" | bc -l
2009-03-25 09:46:01
User: polar
Functions: bc echo
Tags: bc

Useful for quick calculations at the command line. $math_expr is any arithmetic expression (see sample output):



More options in the bc man page.