LinuxQuestions.org - How to use "awk" to do the following seemingly simple work?

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How to use "awk" to do the following seemingly simple work?

1) Given an input file, I want to perform some action to a line subject to some conditions of the next line. For example,

if the next line is "======" then I want to print the current line.
How can such actions be performed using awk?

2) Is there any method for awk to go back one/more line(s) when reading a file?

3) What is the difference between these two intrinsic variables: NR and FNR?

4) Does awk support multidimensional array?

Quote:

Originally Posted by lawrence_lee_lee (Post 3123865)

2) Is there any method for awk to go back one/more line(s) when reading a file?

No.

Quote:

Originally Posted by lawrence_lee_lee (Post 3123865)

Store each line in a transient buffer, compare to current and
print it.

Quote:

Originally Posted by lawrence_lee_lee (Post 3123865)

3) What is the difference between these two intrinsic variables: NR and FNR?

NR is the TOTAL number of records seen, FNR pertains
to the "current file".

Quote:

Originally Posted by lawrence_lee_lee (Post 3123865)

4) Does awk support multidimensional array?

Yes.

Cheers,
Tink