shell script trap functions

include.sh

#!/bin/bash

set -o errexit # exit on errors
set -o nounset # exit on use of uninitialized variable
set -o errtrace # inherits trap on ERR in function and subshell

trap 'traperror $? $LINENO $BASH_LINENO "$BASH_COMMAND" $(printf "::%s" ${FUNCNAME[@]:-})' ERR
trap 'trapexit $? $LINENO' EXIT

function trapexit() {
  echo "$(date) $(hostname) $0: EXIT on line $2 (exit status $1)"
}

function traperror () {
    local err=$1 # error status
    local line=$2 # LINENO
    local linecallfunc=$3
    local command="$4"
    local funcstack="$5"
    echo "$(date) $(hostname) $0: ERROR '$command' failed at line $line - exited with status: $err" 

    if [ "$funcstack" != "::" ]; then
      echo -n "$(date) $(hostname) $0: DEBUG Error in ${funcstack} "
      if [ "$linecallfunc" != "" ]; then
        echo "called at line $linecallfunc"
      else
        echo
      fi
    fi
    echo "'$command' failed at line $line - exited with status: $err" | mail -s "ERROR: $0 on $(hostname) at $(date)" [email protected]
}

function log() {
    local msg=$1
    now=$(date)
    i=${#FUNCNAME[@]}
    lineno=${BASH_LINENO[$i-2]}
    file=${BASH_SOURCE[$i-1]}
    echo "${now} $(hostname) $0:${lineno} ${msg}"
}

Thanks. This is very handy when copy pasted into the beginning of a script. I made it skip the trapexit echo if the exit code was successful for my own use.

What's going on on line 27?

What's going on on line 27?

Newline. More readable replacement is printf '\n' :)

EXIT is always triggered when ERR is. How to make them exclusive ?
How to trap non unset variables since they don't trigger ERR !?

-o nounset results in errexit when an unset variable is referenced: https://www.gnu.org/software/bash/manual/bash.html#The-Set-Builtin-1

Treat unset variables and parameters other than the special parameters ‘@’ or ‘’, or array variables subscripted with ‘@’ or ‘’, as an error when performing parameter expansion. An error message will be written to the standard error, and a non-interactive shell will exit.