Useful bash scripting functions

logging.sh

# foundation function for the actual log-functions to build on
function _log {
  echo "[$(date +%Y%m%d-%T)] $1"
}

# functions for the different log levels
function log_debug {
  # debug messages need to be enabled through an environment varaible
  if [ $DEBUG ]
  then
    _log "DEBUG: $1"
  fi
}
function log_info {
  _log "INFO: $1"
}
function log_warn {
  _log "WARN: $1"
}
function log_error {
  _log "ERROR $1"
}

# For when the process needs to exit with an error message
function die() {
  log_error "$1"
  exit 1
}

Example use

log_info "Checking pre-requisites"
which svn >/dev/null || die "The 'svn' command is not available on the PATH"

To show debug messages

DEBUG=1 my_script.sh