UNIX for Advanced & Expert Users

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++

% echo a/b/c++ | awk -F'/b/c\\++$' '{print $1}'
a

% echo a/b/c+ | awk -F'/b/c++' '{print $1, $2}'
a +

% echo a/b/cccc+ | awk -F'/b/c++' '{print $1, $2}'
a +

% 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: ++

% 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:

% 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:

9.4.6 EREs Matching Multiple Characters
[...]
The behavior of multiple adjacent duplication symbols ( '+', '*', '?', and intervals) produces undefined results.