On 2019-01-23 15:20, Chet Ramey wrote:
> On 1/23/19 10:59 AM, Shen Herbert wrote:
> > Configuration Information [Automatically generated, do not change]:
> > Machine: x86_64
> > OS: linux-gnu
> > Compiler: gcc
> > Compilation CFLAGS: -march=x86-64 -mtune=generic -O2 -pipe
> > -fstack-protector-strong -fno-plt
> > -DDEFAULT_PATH_VALUE='/usr/local/sbin:/usr/local/bin:/usr/bin'
> > -DSTANDARD_UTILS_PATH='/usr/bin' -DSYS_BASHRC='/etc/bash.bashrc'
> > -DSYS_BASH_LOGOUT='/etc/bash.bash_logout' -DNON_INTERACTIVE_LOGIN_SHELLS
> > -Wno-parentheses -Wno-format-security
> > uname output: Linux arch.ishbguy.org 4.20.3-arch1-1-ARCH #1 SMP PREEMPT Wed
> > Jan 16 22:38:58 UTC 2019 x86_64 GNU/Linux
> > Machine Type: x86_64-pc-linux-gnu
> >
> > Bash Version: 5.0
> > Patch Level: 0
> > Release Status: release
> >
> > Description:
> >
> > RETURN trap will inherit last RETURN trap cmd though set +T under bash 5.0
> > or bash 4.4, however, this will not happen under bash 4.3. For example:
> > ```
> > set +T
> > one { trap 'echo in one' RETURN; }
> > all {
> > trap 'echo in all' RETURN
> > one
> > }
> > all
> > ```
> > in bash 5.0 and 4.4 will print:
> > ```
> > in one
> > in one
> > ```
> > in bash 4.3 will print:
> > ```
> > in one
> > in all
> > ```
>
> There is only a single RETURN trap; traps are not local. If a called
> function sets the RETURN trap, it should overwrite the caller's trap,
> and the caller's value should not get restored. Then, when the caller
> returns, and there is a RETURN trap set, it should execute the current
> RETURN trap, not the one it had before it called the second function
> (`one' in this case).
>
> The behavior of bash-4.3 was a bug. I changed it partly as the result of
> this bug report:
>
> http://lists.gnu.org/archive/html/bug-bash/2015-08/msg00130.html
>
> This change made the behavior of the RETURN trap align with the DEBUG and
> ERROR traps.
>
> Chet
> --
> ``The lyf so short, the craft so long to lerne.'' - Chaucer
> ``Ars longa, vita brevis'' - Hippocrates
> Chet Ramey, UTech, CWRU c...@case.edu http://tiswww.cwru.edu/~chet/
OK, I got it. Thank you very much.
--
------------------------------------------
Herbert Shen
Mail: ishb...@hotmail.com
GitHub: https://github.com/ishbguy
------------------------------------------
