creating a unique id string in shell
 

How would I generate a unique id string within a Bash shell? PHP has a nice function called uniquid() that generates a 13 digit unique string. Any suggestions for how to do this in Linux shell scripting? I found random(), but was unsure how to use it. Thanks for any assistance.

r=( $(openssl rand 100000 | sha1sum) ); printf "%s${r[0]:0:13}\n"

If you haven't got|don't want OpenSSL, and you can't|won't use designated devices like /dev/random or the Entropy Gathering Daemon then try using data that changes a lot, like catting disk/network stats from /proc, time, etc etc...

You can use the $RANDOM shell variable, but it is not guaranteed to be unique. Not sure what you need it for, but if is for temporary file names you could try mktemp.

I don't know of a solution, but search Google for a GUID generator. You might find one that you can port to the language/platform of your choice and then execute it from the within the shell.

Re: creating a unique id string in shell
 

- If it doen't need to be random, but just unique, how about a simple counter? Increase by 1 each time you need another identifier, padding with zero's if you need the id's to be fixed length strings.

- If you just need one unique id for each instance of the script, how about it's process id? You get it (in bash/sh) easily with the $$-variable, e.g. "echo $$".

(or maybe I didn't get your question right?)