Re: cut off last lines of a document

Ede Wolf <listac@nebelschwaden.de> writes:
> Am 03.09.23 um 23:16 schrieb paul beard:
> > export COUNT=`wc -l /var/log/messages | tr -d -c '\n[:digit:]'` #
> > export WANT=`echo "$COUNT-3" | bc ` # subtract 3 (or however many)
> > head -$WANT /var/log/messages # display the remainder.

1) there is no need to export the variables
2) don't use backticks, use $() instead
3) if you use 'wc -l <foo' instead of 'wc -l foo' you don't need tr
3b) alternatively, use read: wc -l foo | read COUNT FILENAME
4) the shell can do the math for you: 'head -$((COUNT-3)) foo'

> Thanks, but the problem I currently see here, as with the suggestion
> of Archimedes earlier, I am currently not easily able to convert this
> into a feed from stdin.

Pipe-friendly pure shell solution:

drop_last_three() {
        local a b c d
        read a
        read b
        read c
        while read d ; do
                echo "$a"
                a="$b"
                b="$c"
                c="$d"
        done
}

DES
-- 
Dag-Erling Smørgrav - des@FreeBSD.org