date bash script works under RHEL but not ubuntu - bash

Question

the script from How to keep: daily backups for a week, weekly for a month, monthly for a year, and yearly after that
works under RHEL7 but reports errors when used on two separate ubuntu machines
I do not find what could be wrong with it besides it has loops within loops and some expressions are not quoted
keepdates ()
{
for i in {0..7};
do
((keep[$(date +%Y%m%d -d "-$i day")]++));
done;
for i in {0..4};
do
((keep[$(date +%Y%m%d -d "sunday-$((i+1)) week")]++));
done;
for i in {0..12};
do
DW=$(($(date +%-W)-$(date -d $(date -d "$(date +%Y-%m-15) -$i month" +%Y-%m-01) +%-W)));
for ((AY=$(date -d "$(date +%Y-%m-15) -$i month" +%Y); AY < $(date +%Y); AY++ ))
do
((DW+=$(date -d $AY-12-31 +%W)));
done;
((keep[$(date +%Y%m%d -d "sunday-$DW weeks")]++));
done;
for i in {0..5};
do
DW=$(date +%-W);
for ((AY=$(($(date +%Y)-i)); AY < $(date +%Y); AY++ ))
do
((DW+=$(date -d $AY-12-31 +%W)));
done;
((keep[$(date +%Y%m%d -d "sunday-$DW weeks")]++));
done;
echo ${!keep[#]}
}
The error is:
-bash: ./test.sh: line 18: syntax error near unexpected token `newline'
-bash: ./test.sh: line 18: ` done;'
any idea?
added output under RHEL7
$ bash --version
GNU bash, version 4.2.46(2)-release (x86_64-redhat-linux-gnu)
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
$ date --version
date (GNU coreutils) 8.22
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by David MacKenzie.
$ keepdates; # my custom function but a bash script would do the same
20130106 20140105 20150104 20160103 20170101 20170205 20170305 20170402 20170507 20170604 20170702 20170806 20170903 20171001 20171105 20171203 20171224 20171231 20180107 20180114 20180117 20180118 20180119 20180120 20180121 20180122 20180123 20180124

Answer 1

(I have no fedora but openSUSE 42.3 with GNU bash, Version 4.3.42(1)-release.)
The unnecessary semicolons have already been mentioned above. You call the date command with a fix result in your loops.
I wrote sequencies with $(seq from to) but that's just cosmetics, the {1..3} notation works too, I did not know that before.
The main problem is the nested date call in line 13 and the date call within the double expression evaluation in line 23 of your original post.
I have solved that by pulling out the fixed variables motm (MiddleOfTheMonth) and EY (EndYear).
For Line 13:
in this for condition $(date +%Y-%m-15) is fixed, why should the value be recalculated every time, same for $(date +%Y), try this line alone:
i=5; for ((AY=$(date -d "$(date +%Y-%m-15) -$i month" +%Y); AY < $(date +%Y); AY++ )); do echo $AY; done
-bash: syntax error near unexpected token `newline'
and with the $mdtm:
motm="2018-01-15"; i=5; for ((AY=$(date -d "$motm -$i month" +%Y); AY < $(date +%Y); AY++ )); do echo $AY; done
2017
For Line 23 you can observe the for condition:
i=2; for ((AY=$(($(date +%Y)-i));AY<2018;AY++));do echo $AY; done
-bash: syntax error near unexpected token `newline'
and
i=2; for ((AY=$((2018-i));AY<2018;AY++));do echo $AY; done
2016
2017
I do not know what goes wrong in the bash. I can only tell you how to write it down so it works.
This one produce the same on openSUSE and Ubuntu 16.04.3 LTS
#!/bin/bash
keepdates ()
{
local -a keep
for i in $(seq 0 7)
do
(( keep[$(date +%Y%m%d -d "-$i day")]++ ))
done
for i in $(seq 0 4)
do
(( keep[$(date +%Y%m%d -d "sunday-$((i+1)) week")]++ ))
done
motm=$(date +%Y-%m-15)
for i in $(seq 0 12)
do
DW=$(( $(date +%-W)-$(date -d $(date -d "$motm -$i month" +%Y-%m-01) +%-W) ))
for (( AY=$(date -d "$motm -$i month" +%Y); $AY < $(date +%Y); AY++ ))
do
(( DW+=$(date -d $AY-12-31 +%W) ))
done
(( keep[$(date +%Y%m%d -d "sunday-$DW weeks")]++ ))
done
for i in $(seq 0 5)
do
DW=$(date +%-W)
EY=$(date +%Y)
for (( AY=$(( EY-i )); $AY < $EY; AY++ ))
do
(( DW+=$(date -d $AY-12-31 +%W) ))
done
(( keep[$(date +%Y%m%d -d "sunday-$DW weeks")]++ ))
done
echo ${!keep[#]}
}
keepdates