log_functions.sh #3

#!/bin/bash
#==============================================================================
# Copyright and license info is available in the LICENSE file included with
# the Server Deployment Package (SDP), and also available online:
# https://workshop.perforce.com/view/p4-sdp/main/LICENSE
#------------------------------------------------------------------------------

#------------------------------------------------------------------------------
# Version ID Block. Relies on +k filetype modifier.
# VersionID='$Id: //p4-sdp/dev_rebrand/Server/Unix/p4/common/bin/log_functions.sh#3 $ $Change: 31617 $'

#==============================================================================
# This library contains runctions related to handling log files.

#------------------------------------------------------------------------------
# Function: get_old_log_timestamp ($log)
#
# Get the last modified timestamp of the old log in a cross-platform manner.
# If we don't get a correct value using 'stat' (which varies across the
# UNIX/Linux/MacOSX spectrum), use the current time as a fallback. In that
# case, the timestamp will reflect the time the log was moved rather than when
# it was last modified, but that's still reasonable.  The file timestamp will
# still have the correct last-modified time.
#------------------------------------------------------------------------------
function get_old_log_timestamp () {
   local log=${1:-}
   local oldLogTimestamp=
   [[ -n "$log" ]] || return

   if [[ "$(uname -s)" == "Darwin" ]]; then
      oldLogTimestamp=$(stat -L -f %Sm -t '%Y-%m-%d-%H%M%S' "$log" 2>/dev/null)
   else
      oldLogTimestamp="$(stat -L -c '%10y' "$log" | sed -e 's@[.].*$@@g' -e 's@:@@g' -e 's@ @-@g')"
   fi

   [[ "$oldLogTimestamp" =~ ^[2-9]{1}[0-9]{3}- ]] ||
      oldLogTimestamp=$(date +'%Y-%m-%d-%H%M%S')

   echo "$oldLogTimestamp"
}