shell/bash generate random alphanumeric string

bash.generate.random.alphanumeric.string.sh

#!/bin/bash
# bash generate random alphanumeric string
#

# bash generate random 32 character alphanumeric string (upper and lowercase) and 
#NEW_UUID=$(cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 32 | head -n 1)

# MAC is "special" and requires LC_CTYPE override & fold gets grumpy LOOK AT COMMENTS FROM OG
# NEW_UUID=$(cat /dev/urandom | LC_CTYPE=C tr -dc 'a-zA-Z0-9' | head -c 32)
# ALSO got all weird and had fractions / wild characters in selector with LC_CTYP=C
NEW_UUID=$(cat /dev/urandom | LC_CTYPE=C tr -dc 'abcdefghijklmnopqrstuvwxyz0123456789' | head -c 32)

# bash generate random 32 character alphanumeric string (lowercase only)
cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 32 | head -n 1

# Random numbers in a range, more randomly distributed than $RANDOM which is not
# very random in terms of distribution of numbers.

# bash generate random number between 0 and 9
cat /dev/urandom | tr -dc '0-9' | fold -w 256 | head -n 1 | head --bytes 1

# bash generate random number between 0 and 99
NUMBER=$(cat /dev/urandom | tr -dc '0-9' | fold -w 256 | head -n 1 | sed -e 's/^0*//' | head --bytes 2)
if [ "$NUMBER" == "" ]; then
  NUMBER=0
fi

# bash generate random number between 0 and 999
NUMBER=$(cat /dev/urandom | tr -dc '0-9' | fold -w 256 | head -n 1 | sed -e 's/^0*//' | head --bytes 3)
if [ "$NUMBER" == "" ]; then
  NUMBER=0
fi