This is template for scripted tasks that need to be silent unless error.

Bash template

#!/usr/bin/env bash
# Copyright (c) 2014, TOGGL LLC
# All rights reserved.
# Published under New BSD license

# Set configuration variables on top


# Error handling and logging
LOG_NAME="`basename $0 .sh`.log"
LAST_LINES_TO_SHOW_ON_ERROR=20

set -o pipefail # trace ERR through pipes
set -o errtrace  # trace ERR through functions
set -o nounset   set -o errexit   
exec 3>&1 4>&2 # store original stdin in 3 and stderr in 4
exec >> ${LOG_NAME}
exec 2>&1 # Direct output to to file

log() {
  echo "$(date) $1"
}

restore_file_descriptors() {
 exec 1>&3 2>&4 # restore original file descriptors
}

err_handler() {
 restore_file_descriptors
 echo "Got error, see last ${LAST_LINES_TO_SHOW_ON_ERROR} lines of log"
 tail -n${LAST_LINES_TO_SHOW_ON_ERROR} ${LOG_NAME} 1>&2
 exit 10
}

trap err_handler ERR
trap restore_file_descriptors EXIT

log "Started $(basename $0)"

# Your code starts here =================================================

LICENSE

Copyright (c) 2014, TOGGL LLC
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

3. Neither the name of the TOGGL LLC nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.