UNIX for Dummies Questions & Answers

not all awk's can reference the $0 in the END block - AiX's doesn't.
As an alternative:

Code:

nawk '/^\^\^/ {print ">" FILENAME;f=1;next}f&&f--' myFile

getline! Of course!
Thanks!

vgersh99,

Would you mind explaining me the last part (f=1;next}f&&f--) of your code?
Thanks!

X

f=1 assign 1 to f as we need to print the next line. Had we had the need to print 3 lines below the matched pattern, f=3

f&&f-- if f>0, subtract 1 from f. When the boolean condition is true, the awk EXPLICIT action is print the current record. Which is the same as writing:

Code:

f&&f-- {print $0}

NOTE: I don't like using 'getline' as it breaks the logic/paradigm of data flow in awk which is process each record/line one at a time. I only use 'getline' when I need to 'read in' an additional lookup/config file inside awk in addition of parsing the specified file in the normal manner. It's a matter of taste I reckon...

Guys,
Thank you so very much!
X

Regarding the original code and why it failed, my guess is that your problem results from a misunderstanding of how RS is interpreted by your AWK.

POSIX states that only the first character of RS is used as the record separator. If RS consists of more than one character, the behavior is undefined.

Many AWK implementations (notably, the ones most likely to be found on a linux system, including gawk, mawk, and busybox's awk) treat a multicharacter RS as a regular expression.

So, one of two things is likely happening. Either your AWK is treating RS as the single character ^, in which case it's not splitting on the character sequence you intend. Or, your AWK is treating it as a regular expression, in which case it is also not splitting on the character sequence you intend.

If it's treating RS as a regular expression, what does ^^ mean? I'm not certain how AWK implementations which support regular expressions in RS handle anchors (^ and $), since in that context a newline isn't exactly meaningful (it is, afterall, what one is attempting to define when setting RS).

... after a few minutes spent dusting off and booting a 6 yr old version of debian with mawk ...

mawk supports multicharacter, regular expression RS values, and, as expected, RS='^^' does not split records on ^^. However, RS='\^\^' did the trick.

Regards,
Alister