Re: setting a variable from a function called from PS1

[Greg Wooledge]

On Wed, Aug 25, 2010 at 11:20:28AM -0500, E R wrote:
> I've been trying to get a function called from PS1 to set a variable, e.g.:
> 
> num=1
> 
> function xyz {
>  ((num++))
>  date; echo "num: $num"
> }
> 
> PS1="\$(xyz): "

The problem here is that the command substitution (the $(...) bit)
creates a subshell.  The function is executed in a subshell, so any
changes it makes to global variables are lost when the subshell exits.

> In this example, the global value of num doesn't change if it is
> called from PS1. However num does get incremented if xyz is called
> directly.
> 
> Is there a way I can have a function called from PS1 change the value
> of a global variable?

The easiest way would be not to use a function at all:

imadev:~$ PS1='$((++number))\$ '
1$ 
2$ 
3$