README

Demonstrates techniques for generating unique ids in scripts.

TODO:

• crypto hash
• nanoid https://github.com/ai/nanoid

UUIDGEN

# macosx
uuidgen

# install uuidgen on debian
apt-get install uuid-runtime
uuidgen

Using timestamp from date

date +%s

# macosx
$ date -r 1282368345
Sat Aug 21 07:25:45 CEST 2010
$ date -r 1282368345 +%Y-%m-%d
2010-08-21

$ date -d @1282368345
Sat Aug 21 07:25:45 CEST 2010
$ date -d @1282368345 --rfc-3339=date
2010-08-21

Random (bash & zsh)

# random number
echo $RANDOM

# random number between 1 and 10
echo "$(( ( RANDOM % 10 )  + 1 ))"

/dev/random

LC_CTYPE=C tr -dc A-Za-z0-9 < /dev/random | head -c 60 | xargs
# or
head /dev/urandom | tr -dc a-f0-9 | head -c 40

cksum

This technique can be used for consistent hashing

# take a string and cksum it.
echo $(echo "hashingstring" | cksum | cut -f 1 -d \ )

head /dev/urandom | tr -dc a-f0-9 | head -c 40

Resources

• /dev/random example here
• nodejs uuid-support-in-the-crypto-module