Greg Wooledge wrote in
<20250618140055.gf28...@wooledge.org>:
|On Wed, Jun 18, 2025 at 04:57:01 +0300, nkkralev--- via Bug reports \
|for the GNU Bourne Again SHell wrote:
|> to occur.]#test1
|> /bin/bash -c 'set -e ; /bin/echo $(ls /doesnt_exist) ; echo print1'
|> #and the stdout/stderr displayed is:
|> ls: cannot access '/doesnt_exist': No such file or directoryprint1
|
|set -e is NOT an error catching mechanism. The fact that a command
|substitution used as an argument to an outer command had a nonzero
|exit status is not relevant to set -e.
|
|Only the outer command's exit status matters.
|
|hobbit:~$ bash -e -c 'true $(false); echo survived'
|survived
|hobbit:~$ bash -e -c 'false $(false); echo survived'
|hobbit:~$ bash -e -c 'false $(true); echo survived'
|hobbit:~$
|
|set -e may have originally been conceived as an error catching mechanism,
|but the implementation does not conform to that idea, never has, and
|never will. Now, nearly five decades later, set -e is just a historic
|artifact, and its behavior is specified by a committee to try to provide
|backward compatibility for scripts that use it.
|
|It is a TERRIBLE idea to use it in any new scripts. You should perform
|your own error checking instead. Yes, by hand. There is no other way
|that actually works.
..this paradigm has however not spread widely, just yesterday flew
by (still in tmux history):
commit 611c1457ff32cbb39263139b599eb9b6058709fb
Author: Ed Maste <ema...@freebsd.org>
AuthorDate: 2025-06-05 18:50:03 +0000
Commit: Ed Maste <ema...@freebsd.org>
CommitDate: 2025-06-17 17:40:33 +0000
release: Add set -e to abort upon failure
We don't want to blindly continue and produce broken VM images if
something goes wrong.
Reviewed by: cperciva
Event: Kitchener-Waterloo Hackathon 202506
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D50711
---
release/scripts/mk-vmimage.sh | 1 +
1 file changed, 1 insertion(+)
diff --git a/release/scripts/mk-vmimage.sh b/release/scripts/mk-vmimage.sh
index 3ca369b04d8e..d9197de66695 100755
--- a/release/scripts/mk-vmimage.sh
+++ b/release/scripts/mk-vmimage.sh
@@ -29,6 +29,7 @@
# mk-vmimage.sh: Create virtual machine disk images in various formats.
#
#
+set -e
|If you don't like that, then use a better programming language.
|
|See also <https://mywiki.wooledge.org/BashFAQ/105>.
--End of <20250618140055.gf28...@wooledge.org>
--steffen
|
|Der Kragenbaer, The moon bear,
|der holt sich munter he cheerfully and one by one
|einen nach dem anderen runter wa.ks himself off
|(By Robert Gernhardt)
