Does set -e behave differently here
set -e;
function foo {
}
vs.
function foo {
set -e;
}
does set -e belong inside functions? Does set -e declared outside of functions, affect "nested" functions inside a shell file? What about the inverse? Should we call local set -e lol?
Note: the statements here apply to Bash version 4.0.35 and up. Implementations of set -e vary wildly among different shells/versions. Follow Stéphane's advice and don't use set -e.
man bash in the Shell Builtin Commands/set section explains things pretty well though the text is a little dense and requires a bit of focus. To your specific questions the answers are:
set -e behave different here...vs.. - Depends on what you mean by "differently" but I suspect you'd consider the answer "no"...there are no tricky scoping rules. It acts quite linearlly.set -e in a function and then encounter a non-zero status after return? Yes, this will exit.
set -e.
– Stéphane Chazelas
Nov 18 '17 at 11:35
set -e inside a function affect the whole shell? Because this question - https://unix.stackexchange.com/questions/407385/any-command-in-my-terminal-that-exits-with-non-zero-code-closes-my-terminal-wind
– Alexander Mills
Nov 29 '17 at 01:18
local vars). (If you ever use set -x to debug and put it in a function you'll see this in action.) Again, I've only tested with Bash 4.4... earlier (much earlier?) versions may have different behavior.
– B Layer
Nov 29 '17 at 03:55
set -e; (false; echo one) | cat; echo two In this code the standard demands that one must not be printed and the subshell must exit. Any shell showing different behavior is not POSIX conform.
– Mecki
Jan 05 '24 at 17:30
Solution to avoid any headaches:
function foo {
(
set -e;
)
}
(Just use a subshell). Sometimes to make it both confusing and pretty, I do this:
function foo {(
set -e;
# the rest goes here
)}
{( ... )} is not required. If you want a function to run in a subshell, just declare it as foo( ) ( ... code ... ). This is perfectly valid according to POSIX standard. Function bodies can either be enclosed in { ... } or ( ... ), depending if you want to run it in the same shell or in a subshell.
– Mecki
Jan 05 '24 at 14:14
set -ein a script complex enough as to need functions. Do proper error handling instead. – Stéphane Chazelas Nov 18 '17 at 11:27set -ewas never supposed to be a replacement for error handling but a safeguard to avoid catastrophic failures if handling error has been overlooked and continuing executing a script after a command failed can easily have crazy consequences, like massive loss of data. – Mecki Jan 05 '24 at 17:33