math

[!NOTE|label:references:]

sum

[!INFO|label:references:]

awk

$ seq 10 | awk '{s+=$1} END {print s}'
55

# or
$ awk 'BEGIN{print '"1+2+3"'}'
6

file sizes

$ ls -l
total 12
-rw-r--r--  1 marslo staff 3480 Dec 21 21:21 README.md
-rw-r--r--  1 marslo staff 7516 Dec 21 21:21 SUMMARY.md
drwxr-xr-x  7 marslo staff  224 Sep 19 19:52 artifactory
drwxr-xr-x 15 marslo staff  480 Dec 21 21:19 cheatsheet
drwxr-xr-x 12 marslo staff  384 Aug 17 21:11 devops
drwxr-xr-x  9 marslo staff  288 Sep 29 17:31 jenkins
drwxr-xr-x 10 marslo staff  320 Sep 19 19:52 linux
drwxr-xr-x  9 marslo staff  288 Sep 19 19:52 osx
drwxr-xr-x  6 marslo staff  192 Aug 17 21:11 programming
drwxr-xr-x 27 marslo staff  864 Aug 17 22:10 screenshot
drwxr-xr-x  7 marslo staff  224 Oct 11 19:41 tools
drwxr-xr-x  8 marslo staff  256 Aug 30 16:39 vim
drwxr-xr-x  5 marslo staff  160 Aug 17 21:11 virtualization

$ ls -l | awk '{sum += $5} END {print sum}'
14676

datamash

[!TIP|label:reference:]

$ seq 10 | datamash sum 1
55

bc

  • paste + bc

    $ seq 10 | paste -sd+ -
    1+2+3+4+5+6+7+8+9+10
    
    $ seq 10 | paste -sd+ - | bc
    55
  • xargs + bc

    $ seq 10 | xargs printf "- - %s" | xargs | bc
    55
  • sed + bc

    $ seq 10 | sed 's/^/.+/' | bc
    1
    3
    6
    10
    15
    21
    28
    36
    45
    55

$ seq 10 | jq -s 'add'
55

$ f=$(seq 10)
$ echo $(( ${f//$'\n'/+} ))
55

# or
$ echo $(( $(seq 10 | tr "\n" "+") 0 ))
55
# or from file
$ echo $(( $( tr "\n" "+"  < /tmp/test) 0 ))

sum from file

[!NOTE|label:sample file:]

$ cat numbers.txt
73.27
218.38
14.15
9.18
16.60
  • awk

    
    $ awk '{ sum += $1 } END { print sum }' numbers.txt
    331.58
  • paste && bc

    $ paste -sd+ numbers.txt
    73.27+218.38+14.15+9.18+16.60
    
    $ paste -sd+ numbers.txt | bc
    331.58
    • Σn where 1<=n<=100000

      $ seq 100000 | paste -sd+ | bc -l
      5000050000
  • jq

    $ paste -sd' ' numbers.txt | jq -s add
    331.58

number conversion

[!NOTE|label:references:]

ibase and obase params order matters, but not always. Hex values must be in UPPERCASE.

  • the decimal can be ignored in ibase or obase, or we can say, the default ibase and obase are all 10.

CONVERT
IN BC
OUTPUT

八进制 → 二进制

echo "ibase=8; obase=2; 77" | bc

111111

十进制 → 十六进制

echo "obase=16; 255" | bc

FF

十六进制 → 十进制

echo "ibase=16; FF" | bc

255

二进制 → 十进制

echo "ibase=2; 101010" | bc

42

#!/usr/bin/env bash

function convertBase() {
  local from_base=''
  local to_base=''
  local value=''
  local upper=false

  while [[ $# -gt 0 ]]; do
    case "$1" in
      -f|--from  ) from_base="$2" ;  shift 2 ;;
      -t|--to    ) to_base="$2"   ;  shift 2 ;;
      -v|--value ) value="$2"     ;  shift 2 ;;
      -u|--upper ) upper=true     ;  shift   ;; # uppercase hex
      -h|--help  ) echo "Usage: convertBase -f <from_base> -t <to_base> -v <value> [-u]"
                   echo "Supported bases: bin, dec, oct, hex"
                   return 0
                   ;;
      *          ) echo "Unknown option: $1" >&2; return 1 ;;
    esac
  done

  # Map base names to numeric bases for bc
  declare -A base_map=(
    [bin]=2
    [oct]=8
    [dec]=10
    [hex]=16
  )

  local ibase="${base_map[$from_base]}"
  local obase="${base_map[$to_base]}"

  if [[ -z "$ibase" || -z "$obase" ]]; then
    echo "Error: Unsupported base. Use bin, dec, oct, hex." >&2
    return 1
  fi

  # For hex input, force uppercase since bc expects that
  if [[ "$from_base" == "hex" ]]; then
    value="${value^^}"
  fi

  # Use bc to convert
  result=$(echo "obase=$obase; ibase=$ibase; $value" | bc)

  # Format output (uppercase optional)
  if [[ "$upper" == true && "$to_base" == "hex" ]]; then
    result="${result^^}"
  fi

  echo "$result"
}
# usage
$ convertBase -f hex -t dec -v FF         # → 255
$ convertBase -f bin -t dec -v 1011       # → 11
$ convertBase -f dec -t hex -v 255        # → ff
$ convertBase -f dec -t hex -v 255 -u     # → FF
$ convertBase -f dec -t bin -v 42         # → 101010
$ convertBase -f oct -t hex -v 77         # → 3F
$ convertBase -f bin -t oct -v 110101     # → 65
  • supported base keywords

NAME
BASE
DESCRIPTION

bin

2

Binary

oct

8

Octal

dec

10

Decimal

hex

16

Hexadecimal

Common Bases

CONVERSION TYPE
TOOL / METHOD
EXAMPLE

Base → Decimal

$((base#value))

echo $((2#1010))10

Decimal → Hex

printf

printf "%X\n" 255FF

Decimal → Binary

bc

bc < <(echo "obase=2; 42")101010

Octal → Decimal

$((8#17)) $((017))

echo $((8#17))15

Hex → Decimal

$((16#FF)) $((0xFF))

echo $((16#FF))255

  • base → decimal

BASE
TO
SYNTAX
INTERPRETED NUMBER
OUTPUT (DECIMAL)
DESCRIPTION

2

10

$((2#1011))

1011

11

BINARY

8

10

$((8#17))

17

15

OCTAL

8

10

$((017))

17

15

OCTAL

10

10

$((10#42))

42

42

DECIMAL

16

10

$((16#1A3F))

1A3F

6719

HEXADECIMAL

16

10

$((0x1A3F))

1A3F

6719

HEXADECIMAL

36

10

$((36#Z))

Z

35

ALPHANUMERIC MAX

64

10

$((64#_))

_

63

MAX BASE IN BASH

binary <> decimal <> hexadecimal

[!NOTE]

  • obase : [o]utput base

  • ibase : [i]utput base

# bin -> dec
$ bc <<< 'ibase=2;11111111;11111111;11000000;00000000' | paste -sd. -
255.255.192.0

# bin -> hex
$ bc <<< 'obase=16;ibase=2;11111111;11111111;11000000;00000000' | awk '{ printf "%04s\n", $1 }' | paste -sd. -
00FF.00FF.00C0.0000

# dec -> bin
$ bc <<< 'ibase=10;obase=2;255;255;240;0' | numfmt --format %08f | paste -sd' ' -
11111111 11111111 11110000 00000000

# dec -> hex
$ bc <<< 'ibase=10;obase=16;255;255;240;0' | awk '{ printf "%04s\n", $1 }' | paste -sd. -
00FF.00FF.00F0.0000

# hex -> bin
$ bc <<< 'ibase=16;obase=2;FF;FF;EE;0A' | numfmt --format %08f | paste -sd' ' -
11111111 11111111 11101110 00001010

# hex -> dec
$ bc <<< 'ibase=16;FF;FF;EE;0A' | paste -sd. -
255.255.238.10

to decimal

FROM
TO
COMMAND (BASH)
EXAMPLE
OUTPUT
COMMENT

Binary

Decimal

echo $((2#1010))

2#1010

10

-

Hex

Decimal

echo $((16#FF))

16#FF

255

-

Hex

Decimal

echo $((0xFF))

16#FF

255

0x - convert from hex

Octal

Decimal

echo $((8#77))

8#77

63

-

Octal

Decimal

echo $((077))

8#77

63

0 - convert from octal

  • from hexadecimal

    $ echo "ibase=16; F" | bc
    15
    
    # [o]utput base:       0xA -> 10
    #                       ^
    $ echo "ibase=16; obase=A; F" | bc
    15
    
    # or obase first
    $ echo "obase=10; ibase=16; F" | bc
    15
    
    # or
    $ echo $((0xF))
    15
  • from octal

    # obase (decimal) first
    $ echo "obase=10; ibase=8; 17" | bc
    15
    
    # or
    #                     ╭─ 012 -> 10
    #                     --
    $ echo "ibase=8;obase=12; 17" | bc
    15
    
    # or
    $ echo $((017))
    15

to hexadecimal

[!TIP]

  • if convert from decimal, the ibase can be ignored, or we can say, the default ibase is 10.

FROM
TO
COMMAND
EXAMPLE
OUTPUT

Binary

Hex

echo "obase=16; ibase=2; 101011" | bc

101011 → hex

2B

Octal

Hex

echo "obase=16; ibase=8; 77" | bc

77 (octal) → hex

3F

Decimal

Hex

echo "obase=16; 255" | bc

255

FF

Decimal

Hex

printf "%X\n" 255

255

FF

  • from decimal

    $ echo "obase=16; 15" | bc
    F
    
    # or
    $ echo "ibase=10;obase=16; 15" | bc
    F
  • from octal

    $ echo "obase=16; ibase=8; 17" | bc
    F
    
    # or
    $ printf "%x\n" 017
    f

to octal

FROM
TO
COMMAND
EXAMPLE
OUTPUT

Binary

Octal

echo "obase=8; ibase=2; 1010" | bc

1010 → base 2 → base 8

12

Decimal

Octal

printf "%o\n" 42

42

52

Hex

Octal

echo "obase=8; ibase=16; FF" | bc

FF → hex to octal

377

  • from hexadecimal

    $ echo "ibase=16;obase=8; F" | bc
    17
  • from decimal

    $ echo "obase=8; 15" | bc
    17
    
    # or
    $ echo "ibase=10;obase=8; 15" | bc
    17

to binary

[!NOTE|label:references:]

FROM
TO
COMMAND
EXAMPLE
OUTPUT

Octal

Binary

echo "obase=2; ibase=8; 77" | bc

8#77 → obase=2

111111

Decimal

Binary

echo "obase=2; 42" | bc`

42

101010

Hex

Binary

echo "obase=2; ibase=16; FF" | bc

ibase=16; FF → obase=2

11111111

  • from decimal

    $ bc <<< 'obase=2;15'
    1111
    
    $ bc -l <<< 'obase=2;0;0;15;255' | xargs
    0 0 1111 11111111
    
    $ bc -l <<< 'obase=2;0;0;15;255' | awk '{ printf "%08d\n", $0 }' | xargs
    00000000 00000000 00001111 11111111
    
    $ printf "%08d\n" $(echo "obase=2; 0;0;15;255" | bc) | xargs
    00000000 00000000 00001111 11111111
    
    $ bc <<< 'obase=2; 0;0;15;255' | numfmt --format=%08f | xargs
    00000000 00000000 00001111 11111111

to unicode ( hexadecimal )

[!NOTE|label:references:]

# 0x41 -> `A`; 0x61 -> `a`

# decimal -> hexadecimal
$ printf "$(printf %04x 65)\n"
0041

# \u<4-digits-hex>
$ printf "\u$(printf %04x 65)\n"
A

# \U<8-digits-hex>
$ printf "\U$(printf %08x 67147)\n"
𐙋

$ single_unicode_char="😈"
$ printf %d "'$single_unicode_char"
128520
$ printf "$(printf %08x 128520)\n"
0001f608
$ printf "\U$(printf %08x 128520)\n"
😈
  • more

    $ single_unicode_char="😈"
  • to hexadecimal

    #         ╭─ hexadecimal
    $ printf %x "'$single_unicode_char'"
    1f608
    $ printf %08X "'$single_unicode_char'"
    0001F608
    #                                                               ╭─ hexadecimal
    $ echo -n $single_unicode_char | iconv -t UTF-32LE | od -A n -t x4
     0001f608
    $ printf "\U0001f608"
    😈
    
    # or
    $ printf %#x "'$single_unicode_char"
    0x1f608
    $ printf %#X "'$single_unicode_char"
    0X1F608
    $ printf "\U$(printf %08x 0X1F608)\n"
    😈
    
    # or
    #                                           ╭─ hexadecimal
    $ echo -n $single_unicode_char | od -A n -t x1
     f0 9f 98 88
    $ printf %b "\xf0\x9f\x98\x88"
    😈
    #       ╭─ works without `%b` as well
    $ printf "\xf0\x9f\x98\x88"
    😈
  • to octal

    #         ╭─ octal
    $ printf %o "'$single_unicode_char'"
    373010
    #                                                               ╭─ octal
    $ echo -n $single_unicode_char | iconv -t UTF-32LE | od -A n -t o4
     00000373010
    $ printf "\U$(printf %08x "00000373010")"
    😈
    
    # or
    #       ╭─ without `\n`
    $ echo -n $single_unicode_char | od -A n -t o1
     360 237 230 210
    $ printf %b "\360\237\230\210"
    😈

number converting from file

  • octal

    $ cat -p octal-data-file.txt
    7
    10
    11
    12
    13
    14
    15
    16
    17
    20
    21
    
    # octal -> hexadecimal
    $ ( echo "obase=16; ibase=8" ; cat octal-data-file.txt ) | bc
    7
    8
    9
    A
    B
    C
    D
    E
    F
    10
    11
    
    # octal -> decimal
    $ ( echo "obase=10; ibase=8" ; cat octal-data-file.txt ) | bc
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
  • hexadecimal

    $ cat -pp hex-data-file.txt
    9
    A
    B
    C
    D
    E
    F
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    1A
    1B
    1C
    1D
    1E
    1F
    20
    
    # hexadecimal -> octal
    $ ( echo "obase=8; ibase=16" ; cat hex-data-file.txt ) | bc
    11
    12
    13
    14
    15
    16
    17
    20
    21
    22
    23
    24
    25
    26
    27
    30
    31
    32
    33
    34
    35
    36
    37
    40
    
    # hexadecimal -> decimal
    $ ( echo "obase=10; ibase=16" ; cat hex-data-file.txt ) | bc
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32

advanced computing

[!NOTE|label:references:]

logarithm

  • bc

    $ bc -l <<< 'l(9)/l(3)'
    2.00000000000000000000
    • 🫠

      $ bc -l <<< 'l(512)/l(2)'
      9.00000000000000000008
  • awk

    $ echo 512 | awk '{print log($1)/log(2)}'
    9

power

  • bc

    $ bc <<< '2^3'
    8
  • $(())

    $ echo $(( 2**8 ))
    256

square

$ bc -l <<< 'sqrt(2)'
1.41421356237309504880

$ bc <<< 'sqrt(2)'
1

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