How do I get the effect and usefulness of "set -e" inside a shell function?

Question

set -e (or a script starting with #!/bin/sh -e) is extremely useful to automatically bomb out if there is a problem. It saves me having to error check every single command that might fail.

How do I get the equivalent of this inside a function?

For example, I have the following script that exits immediately on error with an error exit status:

#!/bin/sh -e  echo "the following command could fail:" false echo "this is after the command that fails" 

The output is as expected:

the following command could fail: 

Now I'd like to wrap this into a function:

#!/bin/sh -e  my_function() {     echo "the following command could fail:"     false     echo "this is after the command that fails" }  if ! my_function; then     echo "dealing with the problem" fi  echo "run this all the time regardless of the success of my_function" 

Expected output:

the following command could fail: dealing with the problem run this all the time regardless of the success of my_function 

Actual output:

the following output could fail: this is after the command that fails run this all the time regardless of the success of my_function 

(ie. the function is ignoring set -e)

This presumably is expected behaviour. My question is: how do I get the effect and usefulness of set -e inside a shell function? I'd like to be able to set something up such that I don't have to individually error check every call, but the script will stop on encountering an error. It should unwind the stack as far as is needed until I do check the result, or exit the script itself if I haven't checked it. This is what set -e does already, except it doesn't nest.

I've found the same question asked outside Stack Overflow but no suitable answer.

Answer 1

From documentation of set -e:

When this option is on, if a simple command fails for any of the reasons listed in Consequences of Shell Errors or returns an exit status value > 0, and is not part of the compound list following a while, until, or if keyword, and is not a part of an AND or OR list, and is not a pipeline preceded by the ! reserved word, then the shell shall immediately exit.

In your case, false is a part of a pipeline preceded by ! and a part of if. So the solution is to rewrite your code so that it isn't.

In other words, there's nothing special about functions here. Try:

set -e ! { false; echo hi; }