On Fri, Jan 13, 2017 at 09:46:54AM +0100, Anton Lindqvist wrote:
> Consider the following script which calculates the sum of the first N
> integers recursively:
>
> $ cat >sum.sh <<!
> sum() {
> [ $1 -eq 0 ] && echo $2 || sum $(($1 - 1)) $(($2 + $1))
> }
>
> sum 5
> !
>
> Executing the script with the x option gives the following output:
>
> $ sh -x sum.sh
> + sum 5
> 15
>
> I would expect the recursive calls to be traced, similar to how GNU
> bash/sh behaves. With the patch below applied the output is as expected:
>
> $ sh -x sum.sh
> + sum 5
> + [ 5 -eq 0 ]
> + sum 4 5
> + [ 4 -eq 0 ]
> + sum 3 9
> + [ 3 -eq 0 ]
> + sum 2 12
> + [ 2 -eq 0 ]
> + sum 1 14
> + [ 1 -eq 0 ]
> + sum 0 15
> + [ 0 -eq 0 ]
> + echo 15
> 15
>
> The patch make sure to assigns the TRACE flag to every user-defined
> function if the x option is present. The piece of code that led me to
> this:
>
> $ sed -n 606,607p /usr/src/bin/ksh/exec.c
> old_xflag = Flag(FXTRACE);
> Flag(FXTRACE) = tp->flag & TRACE ? true : false;
Hmmm,
afaik -x has always been local to a function in ksh-like shells.
To enable tracing within function call set -x in the fucntion te be traced.
-Otto
>
> Index: exec.c
> ===================================================================
> RCS file: /cvs/src/bin/ksh/exec.c,v
> retrieving revision 1.68
> diff -u -p -r1.68 exec.c
> --- exec.c 11 Dec 2016 17:49:19 -0000 1.68
> +++ exec.c 12 Jan 2017 20:10:48 -0000
> @@ -796,6 +796,9 @@ define(const char *name, struct op *t)
> if (t->u.ksh_func)
> tp->flag |= FKSH;
>
> + if (Flag(FXTRACE))
> + tp->flag |= TRACE;
> +
> return 0;
> }
