Date: Tue, 04 Jan 2011 16:15:01 -0800 From: Devin Teske <dteske@vicor.com> To: RW <rwmaillists@googlemail.com> Cc: Devin Teske <dteske@vicor.com>, freebsd-questions@freebsd.org Subject: Re: a perl question Message-ID: <1294186501.26849.73.camel@localhost.localdomain> In-Reply-To: <20110104221242.35a1710f@gumby.homeunix.com> References: <117654.42578.qm@web121409.mail.ne1.yahoo.com> <AANLkTinEksoXQAA4ZAziE59h%2BLRTxSgSy2WZy6UaQne%2B@mail.gmail.com> <4D231CB7.2060902@teambox.fr> <86pqsc3774.fsf@red.stonehenge.com> <16ABD485-4B26-47C4-AD19-6B84AB497874@vicor.com> <20110104221242.35a1710f@gumby.homeunix.com>
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On Tue, 2011-01-04 at 22:12 +0000, RW wrote:
> On Tue, 4 Jan 2011 10:01:47 -0800
> Devin Teske <dteske@vicor.com> wrote:
>
> >
> > On Jan 4, 2011, at 9:33 AM, Randal L. Schwartz wrote:
> >
> > >>>>>> "Patrick" == Patrick Bihan-Faou
> > >>>>>> <patrick.bihan-faou@teambox.fr> writes:
> > >
> > > Patrick> cat asdf.txt | grep -v XYZ | grep -v bla
> > >
> > > And yet, you still have the "Useless Use of Cat".
> >
> > I know I'm joining the party late, but... what about:
> >
> > grep -Ev '(XYZ|bla)' asdf.txt
> >
> > or
> >
> > awk '!/XYZ/ && !/bla/ {print}' asdf.txt
> >
> > ok... end useless contribution.
>
> It's odd that people seem to be taking bla-bla so literally, when it's
> clearly a place holder for arbitary text.
Maybe because the OP should have said:
"How do I get the text between [XYZ] and [/XYZ]"
A demarcing field-search is different than a pruning line-search.
This is what the OP was looking for:
awk -v tag=XYZ '
BEGIN { buf = "" }
$0 ~ "\\["tag"\\]", $0 ~ "\\[/"tag"\\]" \
{
if ( match($0, "\\[/"tag"\\]") ) \
{
buf = buf substr($0, 0, RSTART - 1)
sub(".*\\["tag"\\]", "", buf)
sub(/^\n*/, "", buf)
sub(/\n*$/, "", buf)
print buf
buf = ""
next
} else
buf = buf $0"\n"
}
END { if ( length(buf) ) print buf }' asdf.txt
or, if you would prefer to have it all on one line:
awk -v tag=XYZ 'BEGIN { buf = "" } $0 ~ "\\["tag"\\]", $0 ~ "\\[/"tag"\
\]" { if ( match($0, "\\[/"tag"\\]") ) { buf = buf substr($0, 0, RSTART
- 1); sub(".*\\["tag"\\]", "", buf); sub(/^\n*/, "", buf); sub(/\n*$/,
"", buf); print buf; buf = ""; next } else buf = buf $0"\n" } END { if
( length(buf) ) print buf }' asdf.txt
or, if you would like it as an alias:
for bash...
alias between_xyz='awk -v tag=XYZ '\''BEGIN { buf = "" } $0 ~ "\\["tag"\
\]", $0 ~ "\\[/"tag"\\]" { if ( match($0, "\\[/"tag"\\]") ) { buf = buf
substr($0, 0, RSTART - 1); sub(".*\\["tag"\\]", "", buf); sub(/^\n*/,
"", buf); sub(/\n*$/, "", buf); print buf; buf = ""; next } else buf =
buf $0"\n" } END { if ( length(buf) ) print buf }'\'
for csh:
alias between_xyz 'awk -v tag=XYZ '\''BEGIN { buf = "" } $0 ~ "\\["tag"\
\]", $0 ~ "\\[/"tag"\\]" { if ( match($0, "\\[/"tag"\\]") ) { buf = buf
substr($0, 0, RSTART - 1); sub(".*\\["tag"\\]", "", buf); sub(/^\n*/,
"", buf); sub(/\n*$/, "", buf); print buf; buf = ""; next } else buf =
buf $0"\n" } END { if ( length(buf) ) print buf }'\'
Usage:
between_xyz asdf.txt
Of course, this can even be improved upon further...
As a shell function:
# between $what $file [$file ...]
#
# Split out lines between [$what] and [/$what] using awk(1).
#
between()
{
awk -v tag="$1" '
BEGIN { buf = "" }
$0 ~ "\\["tag"\\]", $0 ~ "\\[/"tag"\\]" \
{
if ( match($0, "\\[/"tag"\\]") ) \
{
buf = buf substr($0, 0, RSTART - 1)
sub(".*\\["tag"\\]", "", buf)
sub(/^\n*/, "", buf)
sub(/\n*$/, "", buf)
print buf
buf = ""
next
} else
buf = buf $0"\n"
}
END { if ( length(buf) ) print buf }
' "$@"
}
Or, for those csh users, how about a fancy alias?:
alias between 'awk -v tag="\!^" '\''BEGIN { buf = "" } $0 ~ "\\["tag"\
\]", $0 ~ "\\[/"tag"\\]" { if ( match($0, "\\[/"tag"\\]") ) { buf = buf
substr($0, 0, RSTART - 1); sub(".*\\["tag"\\]", "", buf); sub(/^\n*/,
"", buf); sub(/\n*$/, "", buf); print buf; buf = ""; next } else buf =
buf $0"\n" } END { if ( length(buf) ) print buf }'\'' \!:2-$'
Usage:
between XYZ asdf.txt
AND... (lol)... last but not least...
If you want to have case-insensitivity, you'll have to change:
BEGIN { buf = "" }
to:
BEGIN { IGNORECASE = 1; buf = "" }
NOTE: FYI, when you need to grab text that spans multiple lines between
two field delimiters, C/C++ is superior to perl/awk which excel at line-
based I/O versus block I/O. However, I conclude that the OP wanted
something that was executable from the command-line (considering that
he/she actually gave a basic construct for a perl one-liner (which might
as well be an awk one-liner considering FreeBSD doesn't come with Perl
in the base anymore and thus not every machine is guaranteed to have
perl -- while every machine has awk).
ANOTHER NOTE: The above is not intended to start a language flame-war...
just an observation. If you have observed an easy _and_ convenient
method that _does_ use perl/awk (in a manner more efficient than the
above), I'm sure the OP/list would love it. Otherwise, I really do view
this operation as being easier in C using functions like strchr,
strrchr, etc.
--
Cheers,
Devin Teske
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