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awk cut column based on string

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Homework and Emergencies Emergency UNIX and Linux Support awk cut column based on string
# 8  
Old 02-14-2012
The standard awk is fairly weak. If you don't have access to GNU awk, install it. All the above solutions rely on GNU awk or nawk or at least Sun's xpg awk (which is an old version of nawk).
Code:
awk -v IGNORECASE=1 '{if( match($0,/-Tag:([^[:space:]]*)/,found)) print found[1]; }'

With nawk you might do something similar, but using sub() because nawk's match() isn't as cool as GNU's.
# 9  
Old 02-14-2012
Code:
awk -F"[ :-]" 'tolower($2)~/tag/{print "-"$2":"$3}' yourfile

or
Code:
awk '{split($1,a,":")}tolower(a[1])~/-tag/{print $1}' yourfile

or
Code:
awk '{NF=1;split($1,a,":")}tolower(a[1])~/-tag/' yourfile

Code:
$ cat tst
-tag:messages -P:/var/log/messages -P:/var/log/maillog -K:Error -K:Warning -K:critical
-TAG:messages -P:/var/log/messages -P:/var/log/maillog -K:Error -K:Warning -K:critical
-Tag:messages -P:/var/log/messages -P:/var/log/maillog -K:Error -K:Warning -K:critical
-tAG:messages -P:/var/log/messages -P:/var/log/maillog -K:Error -K:Warning -K:critical
$ awk -F"[ :-]" 'tolower($2)~/tag/{print "-"$2":"$3}' tst
-tag:messages
-TAG:messages
-Tag:messages
-tAG:messages
$ awk '{split($1,a,":")}tolower(a[1])~/-tag/{print $1}' tst
-tag:messages
-TAG:messages
-Tag:messages
-tAG:messages
$ awk '{NF=1;split($1,a,":")}tolower(a[1])~/-tag/' tst
-tag:messages
-TAG:messages
-Tag:messages
-tAG:messages

Last edited by ctsgnb; 02-14-2012 at 02:42 PM..
# 10  
Old 02-14-2012
Quote:
Originally Posted by otheus
[..]All the above solutions rely on GNU awk or nawk or at least Sun's xpg awk (which is an old version of nawk).
Are you certain about that otheus? I was under the impression that /usr/xpg4/bin/awk was introduced to Solaris later and does more to approach Posix standards than nawk on Solaris does, which stands for new awk, but that is only relative to ancient original awk...
# 11  
Old 02-14-2012
Not 100% sure, but I know Kernighan was maintaining nawk at least through 2007, and the open BSD project has been maintaining it since, and Solaris, well, I think they brought awk over from System V back in the 90s or maybe even before then with SunOS 4.x

---------- Post updated at 03:54 PM ---------- Previous update was at 03:16 PM ----------

Quote:
Originally Posted by Scrutinizer
Are you certain about that otheus? I was under the impression that /usr/xpg4/bin/awk was introduced to Solaris later and does more to approach Posix standards than nawk on Solaris does, which stands for new awk, but that is only relative to ancient original awk...
Follow-up:
From the FIXES file in awk.zip downloaded from Kernighan's web page:
Code:
Jun 1, 2003:
	subtle change to split: if source is empty, number of elems
	is always 0 and the array is not set.

From Solaris 10 (2005) xpg-awk:
Code:
$ /usr/xpg4/bin/awk 'BEGIN { print split(null,out,FS) }' </dev/null
0

So it would seem Solaris DID keep nawk up-to-date w.r.t Kernighan's version.

Then again....
Code:
Jan 1, 2002:
	length(arrayname) returns number of elements; thanks to 
	arnold robbins for suggestion

And on Sun's implementation:
Code:
$ /usr/xpg4/bin/awk 'BEGIN { split("test",out,/es/); print out[1]; print length(out)}' </dev/null
t
0

Last edited by otheus; 02-14-2012 at 11:01 AM.. Reason: oops! LOL copied wrong output.
# 12  
Old 02-14-2012
@otheus, Interesting, I think though you should be comparing these Solaris nawk, not /usr/xpg4/bin/awk, which should not be following Kernighan's changes, but rather strive to be Posix compliant, no? What is the output of the same commands with nawk ?
# 13  
Old 02-14-2012
First, I think you should split this thread into the Underground forum, for instance, and link to it Smilie

Second, Kerhnighan *is* the author of nawk. What Solaris did to what they call nawk is anyone's guess.

Third, Solaris lists the nawk man page and xpg4/awk man page as the same entity (yet oddly, the files differ vastly in size).

Fourth, nawk explicitly errors with length(arrayname):
Code:
$ nawk 'BEGIN { split("test",out,/es/); print out[1]; print length(out)}' </dev/null
t
nawk: can't read value of out; it's an array name.
 source line number 1

# 14  
Old 02-14-2012
I think you are right, let's do that if you think it is interesting (I do), but what shall we call the thread? /usr/xpg4/bin/awk vs. nawk on Solaris? I thought in post#8 you meant on Solaris /usr/xpg4/bin/awk is an old version of nawk , i.e. the current version on Solaris. And my point was/is that nawk on Solaris is not as compliant as /usr/xpg4/bin/awk and therefore the latter is preferable to nawk on Solaris.

But on rereading you seem to be referring to a recent version of nawk on different systems. But in many other systems nawk is either non-existing or a link to gawk or mawk and on yet others awk is nawk (or bwk).

Yes, Kernighan is the author of nawk, but length() operating on an array is an added feature and is not part of the Posix specification (and unnecessary).
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