Hi,
I would like to propose an improvement to the bash error handling: Add
flag/option "err_return", that will cause a user defined shell functions to
immediately return, when a simple command will return a non-zero status code.
The behavior is similar to the existing '-e', but is different in the following
case. Under current bash, the "Abort On Error" logic is suspended if the
command is executed under "if", "while", "||" or similar. It will make it
possible to implement much better error handling for scripts that involve user
defined functions.
Consider the following simple example:
#! /bin/sh
Function f1 {
cp /new/data /current/data
step1
step2
step3
}
f1 ...
The major issue is that if the /new/data file is missing, or can not be copied
into the /current/data, processing will continue. Same for failures in
following steps.
Adding error handling (that will capture missing /new/data, or processing
errors in step1/2/3), to this script can be done in two ways:
1 - Modifying each functions/script:
Function f1 {
cp /new/data /current/data || return 1
step1 || return 1
step2 || return 1
step3 || return 1
}
2 - Adding 'set -e' (or the equivalent -oerrexit)
The second approach require significantly less effort, especially if there are
large number of scripts/functions. The first approach is not feasible if the
code can not be modified (e.g., code that is used by many scripts that will
need to be retested, or third-party code).
The problem with the second approach is that the 'errexit' is disabled if the
command function is used under "while", "if", "||" or similar.
For example, the following will re-establish the bad behavior, where step1 is
executed even if /new/data is missing:
if f1 ... ; then
echo "OK"
do_more
else
echo "Problem"
fi
The new 'err_return' should address this problem. It will cause 'f1' to return
immediately (with non-zero return code), if the 'cp' fail, without executing
the following step1/2/3.
I believe that adding this option will make it much easier to write reliable
scripts that can properly handle many common error conditions.
Yair Lenga
yair.le...@citi.com
