Advanced `uniq` with “unique part regex”

Question

uniq is a tool that enables once to filter lines in a file such that only unique lines are shown. uniq has some support to specify when two lines a

Answer 1

Not using uniq but using gnu-awk you can get the results you want:

awk -v re='![[:alnum:]]+!' 'match($0, re, a) && !(a[0] in p) {p[a[0]]; print}' file
foo!bar!baz
!baz!quix

• Passing required regex using a command line variable -v re=...
• match function matches regex for each line and returns matched text in [a]
• Every time match succeeds we store matched text in an associative array p and print
• Thus effectively getting uniq function with regex support