Hi all,
I have written so many shell scripts with bash. Most of them contain some identical functionality like reading password, check if input is numeric, etc. and some common constants (EXIT_CODE and ERROR_CODE). I wonder if it's possible to have a common script for organizing all this functions together. e.g.

#!/bin/bash

# Here is a common script for useful utilities and codes

EXIT_CODE=0
FILE_NOT_FOUND=-1
...

readpassword()
{
...
}

If it's ok, please tell me how to invoke the functions defined in the common script. Thanks in advance.

if you look at a rc init script, e.g. /etc/init.d/cron you should see a line such as which is effectively a #include in bash to the funcitons file in that directory, i.e. it will source that file, which (afaik) doesn't actually have to be an executable bash script, just a set of bash commands (i.e. no #!/bin/sh etc...)

Yes you can call the functions of another script with:

source script.sh

I don't understand. Suppose I define thousands of functions in a script(says script.sh). How can I just call one function in the script?

Lets consider that one of your functions inside script.sh it's called xfunc and you want to use in other script called script2.sh.

Edit script2.sh and add a line:
source script.sh

then in this script you will be able to call your function by its name:
xfunc foobar

great. thanks a lot

I wonder why the function can only return a numeric value. How can I return a string? Thanks