Re: Bash: (foo==0)?foo=1:foo=0 valid?

[Robert Nichols]

On 07/02/2011 12:45 PM, Daniel B. Thurman wrote:
> I seem to forget my shell programming
> but is the following statement valid?
>
> ($foo==0)?foo=1:foo=0
>
> I thought it was called the tristate conditional
> operator but in any case I could not find it in
> google.

You need to enclose the entire expression in double parentheses to make
bash parse it as an expression.  Plus, your syntax is slightly wrong:

((($foo==0)?foo=1:0))

or, since within an expression the '$' to reference a variable is optional:

(((foo==0)?foo=1:0))

and, if you want to insert the result directly into a command line:

echo $(((foo==0)?1:0))
or
     echo $(((foo==0)?foo=1:0))