Again on IRC, somebody asked how to remove duplicates from a file, but keeping only the last occurrence of each item. The classic awk idiom awk '!a[$0]++' prints only the first instance of every line. So if the input is, for example foo bar baz foo xxx yyy bar the "normal" output (ie using the [...]
Archive of posts tagged awk
“In-place” editing of files
Temporary files don't bite, so just use them.
Joining files with awk
Join lines from files based on keys