Bash function to generate a secure random alphanumeric string

You can use this Bash function in your .bashrc file to generate a random alphanumeric string easily. This comes in handy when you need to generate a long, secure password for example. Adjust to your needs.

Take the following function and place it in your .bashrc file:

# Generate a random 32 character alphanumeric string (upper and lowercase) and numbers in Bash
random-string() {
  cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w ${1:-32} | head -n 1
}

An example usage and output is

$ random-string
2fORqF7pau7bLafFuJbQNzK2D8yOLMnO

If needed you can add special characters to the tr command, for example (&_a-zA-Z0-9^*@ and ‘.

This will generate a more secure random string, like:

$ random-string
w4LD528^K52@rrYx@vfEg1wKwRSMQXoP
$ random-string
BnhUn_ScM&sIs(Yn0d40PxJKUQN0QkHg
$ random-string
cFg3FRPHB6SXcQ(f8wGr7y1RKSR1i^&i

An example that works on all POSIX systems even Oracle Solaris and IBM AIX. It provides 32 random characters (ie a DWORD byte, or 32 bits), read 8 times):

These random strings generated in Bash make ideal passwords. Rather use PowerShell? Check out “Create strong passwords in Windows“.