Hi,
Putting across a few awk expressions.
Apart from the last, all of them are working.
echo a/b/c | awk -F'/b/c$' '{print $1}'
a
echo a/b/c++ | awk -F'/b/c++' '{print $1}'
a
echo a/b/c++ | awk -F'/b/c++$' '{print $1}'
a/b/c++
Request thoughts on why putting a '$' post double ++ changed everything.
I require a $ as interested in only the last string.
Do let me know workarounds to accomplish the same.
Thanks in advance
In certain positions the + sign is special (one or more occurrences of the previous character):
% echo a/b/c++ | awk -F'/b/c\\++$' '{print $1}'
a
Yes thought of the same but couldn't fit that logic here.
If + is working based on its logic of more occurrences, it shouldn't have worked without the $.
Wondering what effect has putting the $ has?
/b/c++ matches / - b - / - c (one or more occurrences) - + (this one seems to be ignored)
So:
% echo a/b/c+ | awk -F'/b/c++' '{print $1, $2}'
a +
% echo a/b/cccc+ | awk -F'/b/c++' '{print $1, $2}'
a +
/b/c++$ matches / - b - / - c (one or more occurrences) - + (ignored) at the end of the string ($):
These two should be clear:
% echo a/b/c++ |
awk -F'/b/c++$' '{
print "NF:", NF
print "$1:", $1
print "$2:", $2
}'
NF: 1
$1: a/b/c++
$2:
% echo a/b/c++ |
awk -F'/b/c++' '{
print "NF:", NF
print "$1:", $1
print "$2:", $2
}'
NF: 2
$1: a
$2: ++
Here the pattern (FS) is not found:
% echo a/b/c++ |
awk -F'/b/c++$' '{
print "NF:", NF
print "$1:", $1
print "$2:", $2
}'
NF: 1
$1: a/b/c++
$2:
I suppose that the behaviour is unspecified for more than one consecutive quantifiers (+ signs), it siply ignores the second + sign:
% echo a/b/c |
awk -F'/b/c++$' '{
print "NF:", NF
print "$1:", $1
print "$2:", $2
}'
NF: 2
$1: a
$2:
Here only the last a/b/c[c..] matches, because it's at the end of the record:
% echo a/b/ca/b/ccc |
awk -F'/b/c++$' '{
print "NF:", NF
print "$1:", $1
print "$2:", $2
}'
NF: 2
$1: a/b/ca
$2:
This may be implementation specific (I've used GNU awk 4.0 and nawk version 20070501).
I found this in SUS:
9.4.6 EREs Matching Multiple Characters
[...]
The behavior of multiple adjacent duplication symbols ( '+', '*', '?', and intervals) produces undefined results.
Thanks a ton.
I thought myself to be good with regular expressions, probably time to change it 
Let's assume below stands true:
echo a/b/c+ | awk -F'/b/c+' '{print $1, $2}'
a +
echo a/b/c | awk -F'/b/c+' '{print $1, $2}'
a
Request your thoughts on why the below doesn't match when we have a $:
echo a/b/c+ | awk -F'/b/c+$' '{print $1, $2}'
a/b/c+
c+ matches a/b/c.
$ makes it to think that it's the end of line, but it isn't as we have an additional + after that.
Hence, it doesn't qualify for a match & fails.
Exactly (IMHO).
Bingo
This thread appears to be a good reference for regular expressions.
May I request moderators to give it a rating so that folks can refer to it.
Sure, rated as Excellent.
Do the stars next to the thread represent the rating?
Stars were visible even before i gave the request.
Did they read our minds 
Someone must have rated it, don't know who though!
Oh, thought that this functionality should be available only to moderators.
People can make fun this way.
This functionality is public, I rated the thread as per OP requirement.