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How do I use floating-point arithmetic in bash?
(23 answers)
Bash - Calculate the Average of Numbers Inputted
(4 answers)
Closed 1 year ago.
How do you perform floating-point math over variables in bash
the output I get is an integer like number
#! /bin/bash
# finding the average of n numbers
avg=0
read -p "" n
for (( i = 0; i < $n; i++ ))
do
read x
((avg = $avg + $x ))
done
#printf %.3f "$(( avg / n )) "
the goal is to show up to 3 decimal places
3
4
5
6
./avg.sh: line 22: printf: 5 : invalid number
5,000
I tried using | bc but I am missing sth
You can replace the entire loop with awk, which does floating-point math natively:
read -p "" n
awk -v n="$n" '{sum+=$1}; NR==n {printf "%.3f\n", sum/n; exit}'
Explanation: -v n="$n" copies the shell variable n into an awk variable with the same name. {avg+=$1} adds each line of input (well, the first "field" of each line) to a running sum. NR==n {printf "%.3f\n", sum/n; exit} means when it hits the nth line, it prints sum/n to three decimal places and exits.
Found this useful question
Added this section after the for loop
var=$(echo "scale=3; $avg / $n" | bc -l)
echo $var
Here is how you can compute the average of n numbers with POSIX shell arithmetic and have 3 or more decimals:
#!/usr/bin/env sh
decimals=3
# The decimal precision is one digit more than the display decimals,
# so it can have an accurate rounding when formatting.
# The precision factor is 10^(decimals + 1).
precision_factor=$(printf '1%0*d' $((decimals + 1)) 0)
average () {
# Multiply the sum of the arguments by the precision factor,
# and divide by the number of arguments.
# With IFS=+ $* expands to the sum of the arguments $1+$2+$3...
# Example, arguments 5 8 1 7 will expand to 5+8+1+7 because IFS is +
IFS=+ average=$(((($*)*precision_factor)/$#))
# The integer part is the average divided by the precision factor.
integer_part=$((average/precision_factor))
# The decimal part is the average head-stripped from the integer part.
decimal_part=${average#$integer_part}
# Assemble a C-locale (decimal point) string for floating-point average.
float_average="$integer_part.$decimal_part"
# Bash consider floating point arguments to printf must be formatted
# to the current locale. So specify we use the C-locale.
LC_NUMERIC=C printf 'Average: %.*f\n' "$decimals" "$float_average"
}
if [ $# -eq 0 ]; then
printf 'Enter a set of numbers: '
read -r input
average $input
else
average "$#"
fi
How to generate 9 digit random number in shell?
I am trying something like this but it only gave numbers below 32768.
#!/bin/bash
mo=$((RANDOM%999999999))
echo "********Random"$mo
Please help
output should be ********Random453351111
In Linux with /dev/urandom:
$ rnd=$(tr -cd "[:digit:]" < /dev/urandom | head -c 9) && echo $rnd
463559879
I think this should make it
shuf -i 99999999-999999999 -n 1
As a work around, we could just simply ask for 1 random integer, for n times:
rand=''
for i in {1..9}; do
rand="${rand}$(( $RANDOM % 10 ))"
done
echo $rand
Try it online!
Note [1]: Since RANDOM's upper limit has a final digit of 7, there's a slightly lesser change for the 'generated' number to contain 8 or 9's.
Because of RANDOM's limited range, it can only be used to retrieve four base-10 digits at a time. Thus, to retrieve 9 digits, you need to call it three times.
If we don't care much about performance (are willing to pay process substitution costs), this may look like:
#!/usr/bin/env bash
get4() {
local newVal=32768
while (( newVal > 29999 )); do # avoid bias because of remainder
newVal=$RANDOM
done
printf '%04d' "$((newVal % 10000))"
}
result="$(get4)$(get4)$(get4)"
result=$(( result % 1000000000 ))
printf '%09d\n' "$result"
If we do care about performance, it may instead look like:
#!/usr/bin/env bash
get4() {
local newVal=32768 outVar=$1
while (( newVal > 29999 )); do # avoid bias because of remainder
newVal=$RANDOM
done
printf -v "$outVar" '%04d' "$((newVal % 10000))"
}
get4 out1; get4 out2; get4 out3
result="${out1}${out2}${out3}"
result=$(( result % 1000000000 ))
printf '%09d\n' "$result"
Use perl, as follows :
perl -e print\ rand | cut -c 3-11
Or
perl -MPOSIX -e 'print floor rand 10**9'
In Mac terminal, I would like to round a large number.
For example,
At 10^13th place:
1234567812345678 --> 1230000000000000
Or at 10^12th place:
1234567812345678 --> 1235000000000000
So I would like to specify the place, and then get the rounded number.
How do I do this?
You can use arithmetic expansion:
$ val=1234567812345678
$ echo $(( ${val: -13:1} < 5 ? val - val % 10**13 : val - val % 10**13 + 10**13 ))
1230000000000000
$ echo $(( ${val: -12:1} < 5 ? val - val % 10**12 : val - val % 10**12 + 10**12 ))
1235000000000000
This checks if the most significant removed digit is 5 or greater, and if it is, the last significant unremoved digit is increased by one; then we subtract the division remainder from the (potentially modified) initial value.
If you don't want to have to write it this way, you can wrap it in a little function:
round () {
echo $(( ${1: -$2:1} < 5 ? $1 - $1 % 10**$2 : $1 - $1 % 10**$2 + 10**$2 ))
}
which can then be used like this:
$ round "$val" 13
1230000000000000
$ round "$val" 12
1235000000000000
Notice that quoting $val isn't strictly necessary here, it's just a good habit.
If the one-liner is too cryptic, this is a more readable version of the same:
round () {
local rounded=$(( $1 - $1 % 10**$2 )) # Truncate
# Check if most significant removed digit is >= 5
if (( ${1: -$2:1} >= 5 )); then
(( rounded += 10**$2 ))
fi
echo $rounded
}
Apart from arithmetic expansion, this also uses parameter expansion to get a substring: ${1: -$2:1} stands for "take $1, count $2 from the back, take one character". There has to be a space before -$2 (or is has to be in parentheses) because otherwise it would be interpreted as a different expansion, checking if $1 is unset or null, which we don't want.
awk's [s]printf function can do rounding for you, within the limits of double-precision floating-point arithmetic:
$ for p in 13 12; do
awk -v p="$p" '{ n = sprintf("%.0f", $0 / 10^p); print n * 10^p }' <<<1234567812345678
done
1230000000000000
1235000000000000
For a pure bash implementation, see Benjamin W.'s helpful answer.
Actually, if you want to round to n significant digits you might be best served by mixing up traditional math and strings.
Serious debugging is left to the student, but this is what I quickly came up with for bash shell and hope MAC is close enough:
function rounder
{
local value=$1;
local digits=${2:-3};
local zeros="$( eval "printf '0%.0s' {1..$digits}" )"; #proper zeros
# a bit of shell magic that repats the '0' $digits times.
if (( value > 1$zeros )); then
# large enough to require rounding
local length=${#value};
local digits_1=$(( $digits + 1 )); #digits + 1
local tval="${value:0:$digits_1}"; #leading digits, plus one
tval=$(( $tval + 5 )); #half-add
local tlength=${#tval}; #check if carried a digit
local zerox="";
if (( tlength > length )); then
zerox="0";
fi
value="${tval:0:$digits}${zeros:0:$((length-$digits))}$zerox";
fi
echo "$value";
}
See how this can be done much shorter, but that's another exercise for the student.
Avoiding floating point math due to the inherit problems within.
All sorts of special cases, like negative numbers, are not covered.
I'm writing a UNIX script to use the sieve to generate prime numbers. I keep getting a bad modulo division on line 19, and I can't seem to figure out why.
I have tried all kinds of different formatting, not sure what the right way is.
#!bin/bash
read -p "Upper limit? :" answer
theMultiple=2
#populate the array
for ((i=2;i<$answer;i++)); do
sieveArray[$i]=$i
done
#Use Sieve
for ((i=0;i<=${#sieveArray[*]}; i++)); do
if [ $[$(($[${sieveArray[$i]}] % $theMultiple))] -eq 0 ]; then
theMultiple=${sieveArray[$i]}
echo $theMultiple
for ((j=$i;j<${#sieveArray[*]};j++)); do
if [ $[$(($[${sieveArray[$j]}] % $theMultiple))] -eq 0 ]; then
sieveArray[$j]=0
fi
done
fi
done
}
You start filling in your sieveArray at index 2, yet in your main loop you start using it at index zero. The first two elements are probably set to zero by default which causes a division by zero.
You could write it differently with less bash arithmetic and more commands :
#!/bin/bash
limit=$1
sieve="$(seq 2 $limit|sort)"
for n in 2 $(seq 3 2 $limit)
do
sieve="$(comm -23 <(echo "$sieve") <(seq $(($n * $n)) $n $limit|sort))"
done
echo "$sieve"|sort -n
seq is used to generate lists of numbers and multiples.
comm is used to remove the multiples from the sieve variable. As comm expects data sorted un alphabetical order (10 is before 9), the lists of number must be sorted every time.
The for loop is slightly optimized to not include even numbers, except 2.
How to generate a random number within a range in Bash?
Use $RANDOM. It's often useful in combination with simple shell arithmetic. For instance, to generate a random number between 1 and 10 (inclusive):
$ echo $((1 + $RANDOM % 10))
3
The actual generator is in variables.c, the function brand(). Older versions were a simple linear generator. Version 4.0 of bash uses a generator with a citation to a 1985 paper, which presumably means it's a decent source of pseudorandom numbers. I wouldn't use it for a simulation (and certainly not for crypto), but it's probably adequate for basic scripting tasks.
If you're doing something that requires serious random numbers you can use /dev/random or /dev/urandom if they're available:
$ dd if=/dev/urandom count=4 bs=1 | od -t d
Please see $RANDOM:
$RANDOM is an internal Bash function
(not a constant) that returns a
pseudorandom integer in the range
0 - 32767. It should not be used to
generate an encryption key.
You can also use shuf (available in coreutils).
shuf -i 1-100000 -n 1
Try this from your shell:
$ od -A n -t d -N 1 /dev/urandom
Here, -t d specifies that the output format should be signed decimal; -N 1 says to read one byte from /dev/urandom.
you can also get random number from awk
awk 'BEGIN {
# seed
srand()
for (i=1;i<=1000;i++){
print int(1 + rand() * 100)
}
}'
I like this trick:
echo ${RANDOM:0:1} # random number between 1 and 9
echo ${RANDOM:0:2} # random number between 1 and 99
...
There is $RANDOM.
I don't know exactly how it works. But it works.
For testing, you can do :
echo $RANDOM
bash 5.1 introduces a new variable, SRANDOM, which gets its random data from the system's entropy engine and so is not linear and cannot be reseeded to get an identical random sequence. This variable can be used as a substitute for RANDOM for generating more random numbers.
$ echo $((1 + SRANDOM % 10))
4
Random number between 0 and 9 inclusive.
echo $((RANDOM%10))
I wrote several articles on this.
https://linuxconfig.org/generating-random-numbers-in-bash-with-examples
https://linuxconfig.org/random-entropy-in-bash
https://www.cloudsavvyit.com/7572/how-to-generate-better-random-numbers-at-the-bash-command-line/
$ RANDOM=$(date +%s%N | cut -b10-19)
$ echo $(( $RANDOM % 113 + 13 ))
The above will give a number between 13 and 125 (113-1+13), with reasonable random entropy.
If you are using a linux system you can get a random number out of /dev/random or /dev/urandom. Be carefull /dev/random will block if there are not enough random numbers available. If you need speed over randomness use /dev/urandom.
These "files" will be filled with random numbers generated by the operating system. It depends on the implementation of /dev/random on your system if you get true or pseudo random numbers. True random numbers are generated with help form noise gathered from device drivers like mouse, hard drive, network.
You can get random numbers from the file with dd
Reading from /dev/random or /dev/urandom character special files is the way to go.
These devices return truly random numbers when read and are designed
to help application software choose secure keys for encryption. Such
random numbers are extracted from an entropy pool that is contributed
by various random events. {LDD3, Jonathan Corbet, Alessandro
Rubini, and Greg Kroah-Hartman]
These two files are interface to kernel randomization, in particular
void get_random_bytes_arch(void* buf, int nbytes)
which draws truly random bytes from hardware if such function is by hardware implemented (usually is), or it draws from entropy pool (comprised of timings between events like mouse and keyboard interrupts and other interrupts that are registered with SA_SAMPLE_RANDOM).
dd if=/dev/urandom count=4 bs=1 | od -t d
This works, but writes unneeded output from dd to stdout. The command below gives just the integer I need. I can even get specified number of random bits as I need by adjustment of the bitmask given to arithmetic expansion:
me#mymachine:~/$ x=$(head -c 1 /dev/urandom > tmp && hexdump
-d tmp | head -n 1 | cut -c13-15) && echo $(( 10#$x & 127 ))
I have taken a few of these ideas and made a function that should perform quickly if lots of random numbers are required.
calling od is expensive if you need lots of random numbers. Instead I call it once and store 1024 random numbers from /dev/urandom. When rand is called, the last random number is returned and scaled. It is then removed from cache. When cache is empty, another 1024 random numbers is read.
Example:
rand 10; echo $RET
Returns a random number in RET between 0 and 9 inclusive.
declare -ia RANDCACHE
declare -i RET RAWRAND=$(( (1<<32)-1 ))
function rand(){ # pick a random number from 0 to N-1. Max N is 2^32
local -i N=$1
[[ ${#RANDCACHE[*]} -eq 0 ]] && { RANDCACHE=( $(od -An -tu4 -N1024 /dev/urandom) ); } # refill cache
RET=$(( (RANDCACHE[-1]*N+1)/RAWRAND )) # pull last random number and scale
unset RANDCACHE[${#RANDCACHE[*]}-1] # pop read random number
};
# test by generating a lot of random numbers, then effectively place them in bins and count how many are in each bin.
declare -i c; declare -ia BIN
for (( c=0; c<100000; c++ )); do
rand 10
BIN[RET]+=1 # add to bin to check distribution
done
for (( c=0; c<10; c++ )); do
printf "%d %d\n" $c ${BIN[c]}
done
UPDATE: That does not work so well for all N. It also wastes random bits if used with small N. Noting that (in this case) a 32 bit random number has enough entropy for 9 random numbers between 0 and 9 (10*9=1,000,000,000 <= 2*32) we can extract multiple random numbers from each 32 random source value.
#!/bin/bash
declare -ia RCACHE
declare -i RET # return value
declare -i ENT=2 # keep track of unused entropy as 2^(entropy)
declare -i RND=RANDOM%ENT # a store for unused entropy - start with 1 bit
declare -i BYTES=4 # size of unsigned random bytes returned by od
declare -i BITS=8*BYTES # size of random data returned by od in bits
declare -i CACHE=16 # number of random numbers to cache
declare -i MAX=2**BITS # quantum of entropy per cached random number
declare -i c
function rand(){ # pick a random number from 0 to 2^BITS-1
[[ ${#RCACHE[*]} -eq 0 ]] && { RCACHE=( $(od -An -tu$BYTES -N$CACHE /dev/urandom) ); } # refill cache - could use /dev/random if CACHE is small
RET=${RCACHE[-1]} # pull last random number and scale
unset RCACHE[${#RCACHE[*]}-1] # pop read random number
};
function randBetween(){
local -i N=$1
[[ ENT -lt N ]] && { # not enough entropy to supply ln(N)/ln(2) bits
rand; RND=RET # get more random bits
ENT=MAX # reset entropy
}
RET=RND%N # random number to return
RND=RND/N # remaining randomness
ENT=ENT/N # remaining entropy
};
declare -ia BIN
for (( c=0; c<100000; c++ )); do
randBetween 10
BIN[RET]+=1
done
for c in ${BIN[*]}; do
echo $c
done
Maybe I am a bit too late, but what about using jot to generate a random number within a range in Bash?
jot -r -p 3 1 0 1
This generates a random (-r) number with 3 decimal places precision (-p). In this particular case, you'll get one number between 0 and 1 (1 0 1). You can also print sequential data. The source of the random number, according to the manual, is:
Random numbers are obtained through arc4random(3) when no seed is specified, and through
random(3) when a seed is given.
Generate random number in the range of 0 to n (signed 16-bit integer). Result set in $RAND variable. For example:
#!/bin/bash
random()
{
local range=${1:-1}
RAND=`od -t uI -N 4 /dev/urandom | awk '{print $2}'`
let "RAND=$RAND%($range+1)"
}
n=10
while [ $(( n -=1 )) -ge "0" ]; do
random 500
echo "$RAND"
done
What about:
perl -e 'print int rand 10, "\n"; '
You can use a seed, see documentation:
RANDOM=$(date +%s%N | cut -b10-19)
echo $(( $RANDOM % 100 + 1 ))
Based on the great answers of #Nelson, #Barun and #Robert, here is a Bash script that generates random numbers.
Can generate how many digits you want.
each digit is separately generated by /dev/urandom which is much better than Bash's built-in $RANDOM
#!/usr/bin/env bash
digits=10
rand=$(od -A n -t d -N 2 /dev/urandom |tr -d ' ')
num=$((rand % 10))
while [ ${#num} -lt $digits ]; do
rand=$(od -A n -t d -N 1 /dev/urandom |tr -d ' ')
num="${num}$((rand % 10))"
done
echo $num
Random branching of a program or yes/no; 1/0; true/false output:
if [ $RANDOM -gt 16383 ]; then # 16383 = 32767/2
echo var=true/1/yes/go_hither
else
echo var=false/0/no/go_thither
fi
of if you lazy to remember 16383:
if (( RANDOM % 2 )); then
echo "yes"
else
echo "no"
fi
Wanted to use /dev/urandom without dd and od
function roll() { local modulus=${1:-6}; echo $(( 1 + 0x$(env LC_CTYPE=C tr -dc '0-9a-fA-F' < /dev/urandom | head -c5 ) % $modulus )); }
Testing
$ roll
5
$ roll 12
12
Just how random is it?
$ (echo "count roll percentage"; i=0; while [ $i -lt 10000 ]; do roll; i=$((i+1)); done | sort | uniq -c | awk '{print $0,($1/10000*100)"%"}') | column -t
count roll percentage
1625 1 16.25%
1665 2 16.65%
1646 3 16.46%
1720 4 17.2%
1694 5 16.94%
1650 6 16.5%
Generate random 3-digit number
This is great for creating sample data. Example: put all testing data in a directory called "test-create-volume-123", then after your test is done, zap the entire directory. By generating exactly three digits, you don't have weird sorting issues.
printf '%02d\n' $((1 + RANDOM % 100))
This scales down, e.g. to one digit:
printf '%01d\n' $((1 + RANDOM % 10))
It scales up, but only to four digits. See above as to why :)
Pure Bash random number without moduloing
lowerRange=10 # inclusive
upperRange=20 # exclusive
randomNumber=$(( RANDOM * ( upperRange - lowerRange) / 32767 + lowerRange ))
A bash function that uses perl to generate a random number of n digits. Specify either the number of digits or a template of n 0s.
rand() {
perl -E '$ARGV[0]||=""; $ARGV[0]=int($ARGV[0])||length($ARGV[0]); say join "", int(rand(9)+1)*($ARGV[0]?1:0), map { int(rand(10)) } (0..($ARGV[0]||0)-2)' $1
}
Usage:
$ rand 3
381
$ rand 000
728
Demonstration of calling rand n, for n between 0 and 15:
$ for n in {0..15}; do printf "%02d: %s\n" $n $(rand $n); done
00: 0
01: 3
02: 98
03: 139
04: 1712
05: 49296
06: 426697
07: 2431421
08: 82727795
09: 445682186
10: 6368501779
11: 51029574113
12: 602518591108
13: 5839716875073
14: 87572173490132
15: 546889624135868
Demonstration of calling rand n, for n a template of 0s between length 0 and 15
$ for n in {0..15}; do printf "%15s :%02d: %s\n" $(printf "%0${n}d" 0) $n $(rand $(printf "%0${n}d" 0)); done
0 :00: 0
0 :01: 0
00 :02: 70
000 :03: 201
0000 :04: 9751
00000 :05: 62237
000000 :06: 262860
0000000 :07: 1365194
00000000 :08: 83953419
000000000 :09: 838521776
0000000000 :10: 2355011586
00000000000 :11: 95040136057
000000000000 :12: 511889225898
0000000000000 :13: 7441263049018
00000000000000 :14: 11895209107156
000000000000000 :15: 863219624761093
Here is a function I wrote which will output a random number in a desired range>
Description:
random <min> <max>
Generate a random number from min to max, inclusive. Both min and max can be
positive OR negative numbers, and the generated random number can be negative too, so
long as the range (max - min + 1) is less than or equal to 32767. Max must be >= min.
The core of it is this:
random() {
min="$1"
max="$2"
range=$((max - min + 1))
rand=$((min + (RANDOM % range)))
echo "$rand"
}
Usage:
# general form: obtain a random number between min and max, inclusive
random <min> <max>
# Example: obtain a random number from -10 to 10, inclusive
random -10 10
This works from the bash built-in variable RANDOM, which probably just uses C rand() under the hood, since they both have a max value of 32767--see:
https://en.cppreference.com/w/c/numeric/random/rand
https://en.cppreference.com/w/c/numeric/random/RAND_MAX
For the bash documentation, see man bash:
RANDOM
Each time this parameter is referenced, a random integer between 0 and 32767 is generated. The sequence of random numbers may be initialized by assigning a value to RANDOM. If RANDOM is unset, it loses its special properties, even if it is subsequently reset.
Robust, runnable, sourceable version of the script
Here is a much more robust version of my random function above. It includes full error checking, bounds checking, a help menu via random --help or random -h, and a special run_check feature which allows you to source OR run this script so that you can source it to import the random function into any other script--just like you can do in Python!
random.sh <-- click this link to always get the latest version from my eRCaGuy_dotfiles repo.
RETURN_CODE_SUCCESS=0
RETURN_CODE_ERROR=1
HELP_STR="\
Generate a random integer number according to the usage styles below.
USAGE STYLES:
'random'
Generate a random number from 0 to 32767, inclusive (same as bash variable 'RANDOM').
'random <max>'
Generate a random number from 0 to 'max', inclusive.
'random <min> <max>'
Generate a random number from 'min' to 'max', inclusive. Both 'min' and 'max' can be
positive OR negative numbers, and the generated random number can be negative too, so
long as the range (max - min + 1) is less than or equal to 32767. Max must be >= min.
This file is part of eRCaGuy_dotfiles: https://github.com/ElectricRCAircraftGuy/eRCaGuy_dotfiles
"
print_help() {
echo "$HELP_STR" | less -RFX
}
# Get a random number according to the usage styles above.
# See also `utils_rand()` in utilities.c:
# https://github.com/ElectricRCAircraftGuy/eRCaGuy_hello_world/blob/master/c/utilities.c#L176
random() {
# PARSE ARGUMENTS
# help menu
if [ "$1" = "-h" ] || [ "$1" = "--help" ]; then
print_help
exit $RETURN_CODE_SUCCESS
fi
# 'random'
if [ $# -eq 0 ]; then
min=0
max="none"
# 'random max'
elif [ $# -eq 1 ]; then
min=0
max="$1"
# 'random min max'
elif [ $# -eq 2 ]; then
min="$1"
max="$2"
else
echo "ERROR: too many arguments."
exit "$RETURN_CODE_ERROR"
fi
# CHECK FOR ERRORS
if [ "$max" = "none" ]; then
rand="$RANDOM"
echo "$rand"
exit "$RETURN_CODE_SUCCESS"
fi
if [ "$max" -lt "$min" ]; then
echo "ERROR: max ($max) < min ($min). Max must be >= min."
exit "$RETURN_CODE_ERROR"
fi
# CALCULATE THE RANDOM NUMBER
# See `man bash` and search for `RANDOM`. This is a limitation of that value.
RAND_MAX=32767
range=$((max - min + 1))
if [ "$range" -gt "$RAND_MAX" ]; then
echo "ERROR: the range (max - min + 1) is too large. Max allowed = $RAND_MAX, but actual" \
"range = ($max - $min + 1) = $range."
exit "$RETURN_CODE_ERROR"
fi
# NB: `RANDOM` is a bash built-in variable. See `man bash`, and also here:
# https://stackoverflow.com/a/1195035/4561887
rand=$((min + (RANDOM % range)))
echo "$rand"
}
# Set the global variable `run` to "true" if the script is being **executed** (not sourced) and
# `main` should run, and set `run` to "false" otherwise. One might source this script but intend
# NOT to run it if they wanted to import functions from the script.
# See:
# 1. *****https://github.com/ElectricRCAircraftGuy/eRCaGuy_hello_world/blob/master/bash/argument_parsing__3_advanced__gen_prog_template.sh
# 1. my answer: https://stackoverflow.com/a/70662049/4561887
# 1. https://github.com/ElectricRCAircraftGuy/eRCaGuy_hello_world/blob/master/bash/check_if_sourced_or_executed.sh
run_check() {
# This is akin to `if __name__ == "__main__":` in Python.
if [ "${FUNCNAME[-1]}" == "main" ]; then
# This script is being EXECUTED, not sourced
run="true"
fi
}
# ----------------------------------------------------------------------------------------------------------------------
# Main program entry point
# ----------------------------------------------------------------------------------------------------------------------
# Only run main function if this file is being executed, NOT sourced.
run="false"
run_check
if [ "$run" == "true" ]; then
random "$#"
fi
No other dependency is needed:
$(((RANDOM % $((upperBound - lowerBound))) + lowerBound))
The random number range is [lowerBound,upperBound)