using sed :
sed -r 's/\#([0-9]*)/echo $(date -d @\1)/eg' test.txt
output :
ر أغس 24 16:09:55 EET 2016
ll /data/holding/email
ر أغس 24 16:11:46 EET 2016
cat /etc/rsyslog.conf
ر أغس 24 16:13:58 EET 2016
ll /data/holding/web
as my locale language is Arabic :)