[server01 ~]$ date -d@1472200700
Fri 26 Aug 09:38:20 BST 2016

#1472047795
ll /data/holding/email
#1472047906
cat /etc/rsyslog.conf
#1472048038
ll /data/holding/web

while IFS= read -r i; do [[ $i =~ ^#([0-9]{10})$ ]] &&
      date -d@"${BASH_REMATCH[1]}"; done <file.txt

while IFS= read -r i; do if [[ $i =~ ^#([0-9]{10})$ ]]; then printf '#%sn'
   "$(date -d@"${BASH_REMATCH[1]}")"; else printf '%sn' "$i"; fi; done <file.txt

while ...; do ...; done >out.txt

mv out.txt file.txt

$ cat file.txt
#1472047795
ll /data/holding/email
#1472047906
cat /etc/rsyslog.conf
#1472048038
ll /data/holding/web

$ while IFS= read -r i; do [[ $i =~ ^#([0-9]{10})$ ]] && date -d@"${BASH_REMATCH[1]}"; done <file.txt
Wed Aug 24 20:09:55 BDT 2016
Wed Aug 24 20:11:46 BDT 2016
Wed Aug 24 20:13:58 BDT 2016

$ while IFS= read -r i; do if [[ $i =~ ^#([0-9]{10})$ ]]; then printf '#%sn' "$(date -d@"${BASH_REMATCH[1]}")"; else printf '%sn' "$i"; fi; done <file.txt
#Wed Aug 24 20:09:55 BDT 2016
ll /data/holding/email
#Wed Aug 24 20:11:46 BDT 2016
cat /etc/rsyslog.conf
#Wed Aug 24 20:13:58 BDT 2016
ll /data/holding/web

sed -E 's/^#([0-9]+).*$/date -d @1/e'

perl  -MPOSIX -pe 's/^#(d+).*/ctime $1/e'

gawk '/^#/{$0 = strftime("%c", substr($0, 2))};1'

sed -E 's/#(1[0-9]{9})(.*)/echo 1 $(date -d @1)/e' log.file

sed -r 's/#([0-9]*)/echo $(date -d @1)/eg' test.txt

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

$ paste -d 'n' <( sed '2~2d;y/#/@/' epoch.txt | date -f - ) <( sed '1~2d' epoch.txt )
Wed Aug 24 07:09:55 PDT 2016
ll /data/holding/email
Wed Aug 24 07:11:46 PDT 2016
cat /etc/rsyslog.conf
Wed Aug 24 07:13:58 PDT 2016
ll /data/holding/web
$