#!/bin/bash

# A slicker error handling routine

# I put a variable in my scripts named PROGNAME which
# holds the name of the program being run.  You can get this
# value from the first item on the command line ($0).

# Reference: This was copied from <http://www.linuxcommand.org/wss0150.php>

PROGNAME=$(basename $0)

function error_exit
{

#   ----------------------------------------------------------------
#   Function for exit due to fatal program error
#       Accepts 1 argument:
#           string containing descriptive error message
#   ----------------------------------------------------------------

    echo"${PROGNAME}: ${1:-"Unknown Error"}" 1>&2
    exit 1
}

# Example call of the error_exit function.  Note the inclusion
# of the LINENO environment variable.  It contains the current
# line number.

echo"Example of error with line number and message"
error_exit"$LINENO: An error has occurred."

tempfiles=( )
cleanup() {
  rm -f"${tempfiles[@]}"
}
trap cleanup 0

error() {
  local parent_lineno="$1"
  local message="$2"
  local code="${3:-1}"
  if [[ -n"$message" ]] ; then
    echo"Error on or near line ${parent_lineno}: ${message}; exiting with status ${code}"
  else
    echo"Error on or near line ${parent_lineno}; exiting with status ${code}"
  fi
  exit"${code}"
}
trap 'error ${LINENO}' ERR

temp_foo="$(mktemp -t foobar.XXXXXX)"
tempfiles+=("$temp_foo" )

error ${LINENO}"the foobar failed" 2

set -e

lib_name='trap'
lib_version=20121026

stderr_log="/dev/shm/stderr.log"

#
# TO BE SOURCED ONLY ONCE:
#
###~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~##

if test"${g_libs[$lib_name]+_}"; then
    return 0
else
    if test ${#g_libs[@]} == 0; then
        declare -A g_libs
    fi
    g_libs[$lib_name]=$lib_version
fi


#
# MAIN CODE:
#
###~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~##

set -o pipefail  # trace ERR through pipes
set -o errtrace  # trace ERR through 'time command' and other functions
set -o nounset   ## set -u : exit the script if you try to use an uninitialised variable
set -o errexit   ## set -e : exit the script if any statement returns a non-true return value

exec 2>"$stderr_log"


###~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~##
#
# FUNCTION: EXIT_HANDLER
#
###~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~##

function exit_handler ()
{
    local error_code="$?"

    test $error_code == 0 && return;

    #
    # LOCAL VARIABLES:
    # ------------------------------------------------------------------
    #    
    local i=0
    local regex=''
    local mem=''

    local error_file=''
    local error_lineno=''
    local error_message='unknown'

    local lineno=''


    #
    # PRINT THE HEADER:
    # ------------------------------------------------------------------
    #
    # Color the output if it's an interactive terminal
    test -t 1 && tput bold; tput setf 4                                 ## red bold
    echo -e"
(!) EXIT HANDLER:
"


    #
    # GETTING LAST ERROR OCCURRED:
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #

    #
    # Read last file from the error log
    # ------------------------------------------------------------------
    #
    if test -f"$stderr_log"
        then
            stderr=$( tail -n 1"$stderr_log" )
            rm"$stderr_log"
    fi

    #
    # Managing the line to extract information:
    # ------------------------------------------------------------------
    #

    if test -n"$stderr"
        then        
            # Exploding stderr on :
            mem="$IFS"
            local shrunk_stderr=$( echo"$stderr" | sed 's/\: /\:/g' )
            IFS=':'
            local stderr_parts=( $shrunk_stderr )
            IFS="$mem"

            # Storing information on the error
            error_file="${stderr_parts[0]}"
            error_lineno="${stderr_parts[1]}"
            error_message=""

            for (( i = 3; i <= ${#stderr_parts[@]}; i++ ))
                do
                    error_message="$error_message"${stderr_parts[$i-1]}":"
            done

            # Removing last ':' (colon character)
            error_message="${error_message%:*}"

            # Trim
            error_message="$( echo"$error_message" | sed -e 's/^[ \t]*//' | sed -e 's/[ \t]*$//' )"
    fi

    #
    # GETTING BACKTRACE:
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #
    _backtrace=$( backtrace 2 )


    #
    # MANAGING THE OUTPUT:
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #

    local lineno=""
    regex='^([a-z]{1,}) ([0-9]{1,})$'

    if [[ $error_lineno =~ $regex ]]

        # The error line was found on the log
        # (e.g. type 'ff' without quotes wherever)
        # --------------------------------------------------------------
        then
            local row="${BASH_REMATCH[1]}"
            lineno="${BASH_REMATCH[2]}"

            echo -e"FILE:\t\t${error_file}"
            echo -e"${row^^}:\t\t${lineno}
"

            echo -e"ERROR CODE:\t${error_code}"            
            test -t 1 && tput setf 6                                    ## white yellow
            echo -e"ERROR MESSAGE:
$error_message"


        else
            regex="^${error_file}\$|^${error_file}\s+|\s+${error_file}\s+|\s+${error_file}\$"
            if [["$_backtrace" =~ $regex ]]

                # The file was found on the log but not the error line
                # (could not reproduce this case so far)
                # ------------------------------------------------------
                then
                    echo -e"FILE:\t\t$error_file"
                    echo -e"ROW:\t\tunknown
"

                    echo -e"ERROR CODE:\t${error_code}"
                    test -t 1 && tput setf 6                            ## white yellow
                    echo -e"ERROR MESSAGE:
${stderr}"

                # Neither the error line nor the error file was found on the log
                # (e.g. type 'cp ffd fdf' without quotes wherever)
                # ------------------------------------------------------
                else
                    #
                    # The error file is the first on backtrace list:

                    # Exploding backtrace on newlines
                    mem=$IFS
                    IFS='
                    '
                    #
                    # Substring: I keep only the carriage return
                    # (others needed only for tabbing purpose)
                    IFS=${IFS:0:1}
                    local lines=( $_backtrace )

                    IFS=$mem

                    error_file=""

                    if test -n"${lines[1]}"
                        then
                            array=( ${lines[1]} )

                            for (( i=2; i<${#array[@]}; i++ ))
                                do
                                    error_file="$error_file ${array[$i]}"
                            done

                            # Trim
                            error_file="$( echo"$error_file" | sed -e 's/^[ \t]*//' | sed -e 's/[ \t]*$//' )"
                    fi

                    echo -e"FILE:\t\t$error_file"
                    echo -e"ROW:\t\tunknown
"

                    echo -e"ERROR CODE:\t${error_code}"
                    test -t 1 && tput setf 6                            ## white yellow
                    if test -n"${stderr}"
                        then
                            echo -e"ERROR MESSAGE:
${stderr}"
                        else
                            echo -e"ERROR MESSAGE:
${error_message}"
                    fi
            fi
    fi

    #
    # PRINTING THE BACKTRACE:
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #

    test -t 1 && tput setf 7                                            ## white bold
    echo -e"
$_backtrace
"

    #
    # EXITING:
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #

    test -t 1 && tput setf 4                                            ## red bold
    echo"Exiting!"

    test -t 1 && tput sgr0 # Reset terminal

    exit"$error_code"
}
trap exit_handler EXIT                                                  # ! ! ! TRAP EXIT ! ! !
trap exit ERR                                                           # ! ! ! TRAP ERR ! ! !


###~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~##
#
# FUNCTION: BACKTRACE
#
###~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~##

function backtrace
{
    local _start_from_=0

    local params=("$@" )
    if (("${#params[@]}">="1" ))
        then
            _start_from_="$1"
    fi

    local i=0
    local first=false
    while caller $i > /dev/null
    do
        if test -n"$_start_from_" && (("$i" + 1   >="$_start_from_" ))
            then
                if test"$first" == false
                    then
                        echo"BACKTRACE IS:"
                        first=true
                fi
                caller $i
        fi
        let"i=i+1"
    done
}

return 0

#!/bin/bash

source 'lib.trap.sh'

echo"doing something wrong now .."
echo"$foo"

exit 0

bash trap-test.sh

doing something wrong now ..

(!) EXIT HANDLER:

FILE:       trap-test.sh
LINE:       6

ERROR CODE: 1
ERROR MESSAGE:
foo:   unassigned variable

BACKTRACE IS:
1 main trap-test.sh

Exiting!

set -o errexit

set +e
echo"commands run here returning non-zero exit codes will not cause the entire script to fail"
echo"false returns 1 as an exit code"
false
set -e

#This function is used to cleanly exit any script. It does this displaying a
# given error message, and exiting with an error code.
function error_exit {
    echo
    echo"$@"
    exit 1
}
#Trap the killer signals so that we can exit with a good message.
trap"error_exit 'Received signal SIGHUP'" SIGHUP
trap"error_exit 'Received signal SIGINT'" SIGINT
trap"error_exit 'Received signal SIGTERM'" SIGTERM

#Alias the function so that it will print a message with the following format:
#prog-name(@line#): message
#We have to explicitly allow aliases, we do this because they make calling the
#function much easier (see example).
shopt -s expand_aliases
alias die='error_exit"Error ${0}(@`echo $(( $LINENO - 1 ))`):"'

#This is an example useage, it will print out
#Error prog-name (@1): Who knew false is false.
if ! /bin/false ; then
    die"Who knew false is false."
fi

 0  success
 1  incorrect invocation or permissions
 2  system error (out of memory, cannot fork, no more loop devices)
 4  internal mount bug or missing nfs support in mount
 8  user interrupt
16  problems writing or locking /etc/mtab
32  mount failure
64  some mount succeeded

#!/bin/bash
set -o pipefail  # trace ERR through pipes
set -o errtrace  # trace ERR through 'time command' and other functions
function error() {
    JOB="$0"              # job name
    LASTLINE="$1"         # line of error occurrence
    LASTERR="$2"          # error code
    echo"ERROR in ${JOB} : line ${LASTLINE} with exit code ${LASTERR}"
    exit 1
}
trap 'error ${LINENO} ${?}' ERR

# Custom errors
EX_UNKNOWN=1

warning()
{
    # Output warning messages
    # Color the output red if it's an interactive terminal
    # @param $1...: Messages

    test -t 1 && tput setf 4

    printf '%s
'"$@">&2

    test -t 1 && tput sgr0 # Reset terminal
    true
}

error()
{
    # Output error messages with optional exit code
    # @param $1...: Messages
    # @param $N: Exit code (optional)

    messages=("$@" )

    # If the last parameter is a number, it's not part of the messages
    last_parameter="${messages[@]: -1}"
    if [["$last_parameter" =~ ^[0-9]*$ ]]
    then
        exit_code=$last_parameter
        unset messages[$((${#messages[@]} - 1))]
    fi

    warning"${messages[@]}"

    exit ${exit_code:-$EX_UNKNOWN}
}

die() {
        echo $1
        kill $$
}

#!/bin/bash

error_exit()
{
    if ["$?" !="0" ]; then
        log.sh"$1"
        exit 1
    fi
}

#!/bin/bash

cd /home/myuser/afolder
error_exit"Unable to switch to folder"

rm *
error_exit"Unable to delete all files"

action () {
    # Test if the first parameter is non-zero
    # and return straight away if so
    if test $1 -ne 0
    then
        return $1
    fi

    # Discard the control parameter
    # and execute the rest
    shift 1
   "$@"
    local status=$?

    # Test the exit status of the command run
    # and display an error message on failure
    if test ${status} -ne 0
    then
        echo Command ""$@"" failed >&2
    fi

    return ${status}
}

command1 param1 param2 param3...
command2 param1 param2 param3...
command3 param1 param2 param3...
command4 param1 param2 param3...
command5 param1 param2 param3...
command6 param1 param2 param3...

action 0 command1 param1 param2 param3...
action $? command2 param1 param2 param3...
action $? command3 param1 param2 param3...
action $? command4 param1 param2 param3...
action $? command5 param1 param2 param3...
action $? command6 param1 param2 param3...

<<<Error-handling code here>>>

#!/bin/sh

# prints:
#
# --> outer
# --> inner
# ./so_1.sh: line 16: some_failed_command: command not found
# <-- inner
# <-- outer

set -e

outer() {
  echo '--> outer'
  (inner) || {
    exit_code=$?
    echo '--> cleanup'
    return $exit_code
  }
  echo '<-- outer'
}

inner() {
  set -e
  echo '--> inner'
  some_failed_command
  echo '<-- inner'
}

outer

#!/bin/sh

# prints:
#
# --> outer
# --> inner
# ./so_2.sh: line 27: some_failed_command: command not found
# --> cleanup

set -e

outer() {
  echo '--> outer'
  inner &
  wait $! || {
    exit_code=$?
    echo '--> cleanup'
    return $exit_code
  }
  echo '<-- outer'
}

inner() {
  set -e
  echo '--> inner'
  some_failed_command
  echo '<-- inner'
}

outer

# [CLEANUP=cleanup_cmd] run cmd [args...]
#
# `cmd` and `args...` A command to run and its arguments.
#
# `cleanup_cmd` A command that is called after cmd has exited,
# and gets passed the same arguments as cmd. Additionally, the
# following environment variables are available to that command:
#
# - `RUN_CMD` contains the `cmd` that was passed to `run`;
# - `RUN_EXIT_CODE` contains the exit code of the command.
#
# If `cleanup_cmd` is set, `run` will return the exit code of that
# command. Otherwise, it will return the exit code of `cmd`.
#
run() {
  local cmd="$1"; shift
  local exit_code=0

  local e_was_set=1; if ! is_shell_attribute_set e; then
    set -e
    e_was_set=0
  fi

 "$cmd""$@" &

  wait $! || {
    exit_code=$?
  }

  if ["$e_was_set" = 0 ] && is_shell_attribute_set e; then
    set +e
  fi

  if [ -n"$CLEANUP" ]; then
    RUN_CMD="$cmd" RUN_EXIT_CODE="$exit_code""$CLEANUP""$@"
    return $?
  fi

  return $exit_code
}


is_shell_attribute_set() { # attribute, like"x"
  case"$-" in
    *"$1"*) return 0 ;;
    *)    return 1 ;;
  esac
}

#!/bin/sh
set -e

# Source the file with the definition of `run` (previous code snippet).
# Alternatively, you may paste that code directly here and comment the next line.
. ./utils.sh


main() {
  echo"--> main: $@"
  CLEANUP=cleanup run inner"$@"
  echo"<-- main"
}


inner() {
  echo"--> inner: $@"
  sleep 0.5; if ["$1" = 'fail' ]; then
    oh_my_god_look_at_this
  fi
  echo"<-- inner"
}


cleanup() {
  echo"--> cleanup: $@"
  echo"    RUN_CMD = '$RUN_CMD'"
  echo"    RUN_EXIT_CODE = $RUN_EXIT_CODE"
  sleep 0.3
  echo '<-- cleanup'
  return $RUN_EXIT_CODE
}

main"$@"

$ ./so_3 fail; echo"exit code: $?"

--> main: fail
--> inner: fail
./so_3: line 15: oh_my_god_look_at_this: command not found
--> cleanup: fail
    RUN_CMD = 'inner'
    RUN_EXIT_CODE = 127
<-- cleanup
exit code: 127

$ ./so_3 pass; echo"exit code: $?"

--> main: pass
--> inner: pass
<-- inner
--> cleanup: pass
    RUN_CMD = 'inner'
    RUN_EXIT_CODE = 0
<-- cleanup
<-- main
exit code: 0

function handle_error {
    status=$?
    last_call=$1

    # 127 is 'command not found'
    (( status != 127 )) && return

    echo"you tried to call $last_call"
    return
}

# Trap errors.
trap 'handle_error"$_"' ERR