error propagation not working in bash

Question

I have a script which goes as below...

some function definitions on top and one of them is...

function err_out    
{

 trap 'echo "ERROR in $STEP function. EXITING!";exit 1' ERR    
 #some more messages

 exit 1
}

# Main program starts here
trap 'err_out' ERR

#do something
#call some functions
#call cleanup function
#end of script

when ever some error happens in the functions, they are not propagated and err_out function is not called.

I tried #!/bin/bash -E too; that way when there is an error the script exits but what I need is error to be propagated properly to the handler.

Answer 1

From the bash info page:

All other aspects of the shell execution environment are identical between a function and its caller with these exceptions: the DEBUG and RETURN traps are not inherited unless the function has been given the trace attribute using the declare builtin or the -o functrace option has been enabled with the set builtin, (in which case all functions inherit the DEBUG and RETURN traps), and the ERR trap is not inherited unless the -o errtrace shell option has been enabled.

So you need to set -o errtrace at the top of the script for the ERR trap to be propagated into your functions.

Additionally, you need to be careful about that recursive ERR trap in err_out. Did you really want to set a new trap in the error handler, or did you want to display that message? If the latter, just echo it; the trap would only be invoked if an error occurred in your error handler.