On 02.07.21 10:58, hal wrote:
>
> $ dpkg -l | egrep -i '(alsa|pulse)' | awk '{print $1" "$2};'
> ii alsa-utils
> ii apulse:amd64
..
Granted, the egrep as quick to use if that's what one's typing
fingers remember, and day to day, it's only the results which
matter
a damn. But as an aside, is it maybe generically helpful to hint
that awk is a complete text processing language; one that it is
not often fully utilised these days? It'll do it all:
$ dpkg -l | awk -v IGNORECASE=1 '/alsa|pulse/ {print $1" "$2};'
ii alsa-utils
ii debian-pulseaudio-config-override
ii gstreamer1.0-alsa:i386
ii gstreamer1.0-pulseaudio:i386
That its great strength is grepping, via the "/pattern/ {action}"
behaviour, is perhaps clearer for the casual reader when we don't
stop to ignore case:
$ dpkg -l | awk '/alsa|pulse/ {print $1" "$2};'
ii alsa-utils
ii debian-pulseaudio-config-override
ii gstreamer1.0-alsa:i386
ii gstreamer1.0-pulseaudio:i386
As for egrep (over plain grep), "The regular expressions in awk
are a superset of the POSIX specification for Extended Regular
Expressions (EREs). POSIX EREs are based on the regular
expressions accepted by the traditional egrep utility.", quoting the
"GAWK: Effective AWK Programming" pdf.
Incidentally, I found the mawk variant was awk on my beowulf
install. As I prefer to take advantage of a few enhancements
provided by gawk (GNU Awk), I've done a quick: # apt-get install
gawk
I hope that interests someone. It's not often that an
opportunity to espouse the original text Swiss army knife presents
itself.
Erik
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