Re: inherit OLDPWD from environment variable

[Lawrence Velázquez <larryv@xxxxxxx>]

On Fri, Jul 19, 2024, at 9:55 PM, Franklin Yu wrote:
> -    oldpwd = ztrdup(pwd);  /* initialize `OLDPWD' = `PWD' */
> +    oldpwd = zgetenv("OLDPWD");
> +    if (oldpwd == NULL || oldpwd[0] == '\0')
> +        oldpwd = ztrdup(pwd);  /* initialize `OLDPWD' = `PWD' */

If we're going to begin importing OLDPWD from the environment, we
might as well align with other shells for consistency, which means
accepting a zero-length value as is.  This is how bash 5.2.26, dash
0.5.12, ksh93u+ 2012-08-01, mksh R59, and yash 2.56.1 all behave.

-- 
vq