create random string from /dev/urandom (or another length)

echo `cat /dev/urandom |tr -dc "[:alnum:]" | head -c64`

2010-12-06 20:01:56

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What Others Think

On FreeBSD 8.1: tr: Illegal byte sequence
Dereckson · 566 weeks and 6 days ago
That cat's not necessary: echo $(</dev/urandom tr -dc "[:alnum:]" | head -c64)
eightmillion · 566 weeks and 6 days ago
Your variant works only with sh, zsh and bash eightmillion. In tcsh, you'll got "Illegal variable name." as output By the way, head -c doesn't work on OpenBSD.
Dereckson · 566 weeks and 6 days ago
It works on ash, dash, bash, sh, ksh, zsh, and sash. The only reason it doesn't work on csh variants is because they aren't posix compliant with respect to command substitution. Try: echo `</dev/urandom tr -dc "[:alnum:]" | head -c64`
eightmillion · 566 weeks and 5 days ago
Thanks for all your comments. This is my "greeting" command. Maybe another version will be later. I test and use it in my gentoo linux box with bash. I agree that echo not needed. Its just cosmetics.
unixmonkey14859 · 566 weeks and 3 days ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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