Function to return the last return code of a set of pipes. e.g. cat blah | sed blah | awk blah | mysql and you want to know if the mysql command worked ok.

lastpipestatusretval.sh

# As an alternative to the remembering the following syntax:
# true | true | true; echo ${PIPESTATUS[${#PIPESTATUS[@]}-1]} => 0
# true | true | false; echo ${PIPESTATUS[${#PIPESTATUS[@]}-1]} => 1
#
# from bash 4.2 you can also do (more simply):
# true | true | false; echo ${PIPESTATUS[-1]} => 1 (and also: -bash: PIPESTATUS: bad array subscript)
#
# e.g. true | true | true; lastpipestatusretval && echo worked
# e.g. true | true | false; ! lastpipestatusretval && echo failed
# + tmppipestatus=('0' '0' '0')
# + local pipelen=2
# + '[' -z 2 ']'
# + '[' 2 -lt 1 ']'
# + tmppipestatus=0
# + return 0
function lastpipestatusretval() {
  # echo ${PIPESTATUS[@]}
  # 0 0 0 0 0 1
  # ${#PIPESTATUS[@]} =>  length => 6
  local tmppipestatus=(${PIPESTATUS[@]})
  local pipelen=$(( ${#tmppipestatus[@]} -1 )) 
  [ -z "$pipelen" ] && return 1
  [ $pipelen -lt 1 ] && return 1
  # get last value
  tmppipestatus="${tmppipestatus[ $pipelen ]}"
  return $tmppipestatus
}