AWK split file every 50 ocurrences of a string - awk

Question

I have a beginner question about awk.
I am using the line below to split a file into c files, using 'MATCH' as my delimiter.
awk 'BEGIN{flag=0} /MATCH/{flag++;next} {print $0 > (flag ".txt")}' file
My file is very long, but it has the form shown below:
MATCH
a
b
c
d
MATCH
a
b
I want to have the above awk line split my file every 50 'MATCH' ocurrences. The current command creates a new file for each 'MATCH' ocurrence. I am sure there is a simple way to achieve this, but I have not figured it out yet. I have tried using the line below with no luck.
awk 'BEGIN{flag=0} /MATCH/{flag++ == 50;next} {print $0 > (flag ".txt")}' file
I appreciate the help and guidance.

Answer 1

Untested, using any awk:
awk '
/MATCH/ && ( ( (++matchCnt) % 50 ) == 1 ) {
close(out)
out = (++outCnt) ".txt"
}
{ print > out }
' file

Answer 2

Assumptions:
the number of lines in a MATCH block are not known beforehand
the number of lines in a MATCH block could vary
the MATCH lines are to be copied to the output files
Sample input with 9 MATCH blocks:
$ cat file
MATCH
1.1
1.2
MATCH
2.1
2.2
MATCH
3.1
3.2
MATCH
4.1
4.2
MATCH
5.1
5.2
MATCH
6.1
6.2
MATCH
7.1
7.2
MATCH
8.1
8.2
MATCH
9.1
9.2
One awk idea:
awk -v blkcnt=3 ' # for OP case set blkcnt=50
BEGIN { outfile= ++fcnt ".txt" }
/MATCH/ { if (++matchcnt > blkcnt) {
close(outfile)
outfile= ++fcnt ".txt"
matchcnt=1
}
# next # uncomment if the "MATCH" lines are *NOT* to be copied to the output files
}
{ print $0 > outfile }
' file
For blkcnt=3 this generates:
$ head -40 {1..3}.txt
==> 1.txt <==
MATCH
1.1
1.2
MATCH
2.1
2.2
MATCH
3.1
3.2
==> 2.txt <==
MATCH
4.1
4.2
MATCH
5.1
5.2
MATCH
6.1
6.2
==> 3.txt <==
MATCH
7.1
7.2
MATCH
8.1
8.2
MATCH
9.1
9.2
For blkcnt=4 this generates:
$ head -40 {1..3}.txt
==> 1.txt <==
MATCH
1.1
1.2
MATCH
2.1
2.2
MATCH
3.1
3.2
MATCH
4.1
4.2
==> 2.txt <==
MATCH
5.1
5.2
MATCH
6.1
6.2
MATCH
7.1
7.2
MATCH
8.1
8.2
==> 3.txt <==
MATCH
9.1
9.2

Answer 3

If I've understood correctly, the first 50 blocks of a,b,c,d lines should be written to 1.txt, the next 50 to 2.txt and so on.
This can be achieved by building the filename from the integer value of (flag/50) and adding 1 to it (assuming you want the file series to being with 1 and not 0).
The BEGIN block can be removed as variables are set to 0 when first created if no value is given and they are used numerically.
Thus the following should achieve the desired output:
awk '/MATCH/{flag++;next} {print $0 >(int(flag/50)+1 ".txt")}' file

Answer 4

so while this isn't a complete solution, it does showcase how to capture each group of rows with each "MATCH", so once you count off every 50, then print them out in one shot, bearing in mind one needs to trim out the tail "MATCH" and save it for the next round
nice jot 53 | mawk 'NR % 6 != 1 || ($!NF = "MATCH")^_' |
mawk '{ printf(" :: input row(s) = %8u\n ::" \
" output row # = %8u\n " \
"-------------------\n %s%s " \
"----END-NEW-ROW----\n\n", NF^!!NF, NR, $!(NF = NF), ORS)
}' RS='(^)?MATCH\r?\n' ORS='MATCH\n' FS='\n' OFS='\f'
:: input row(s) = 1
:: output row # = 1
-------------------
MATCH
----END-NEW-ROW----
:: input row(s) = 6
:: output row # = 2
-------------------
2
3
4
5
6
MATCH
----END-NEW-ROW----
:: input row(s) = 6
:: output row # = 3
-------------------
8
9
10
11
12
MATCH
----END-NEW-ROW----
:: input row(s) = 6
:: output row # = 4
-------------------
14
15
16
17
18
MATCH
----END-NEW-ROW----
:: input row(s) = 6
:: output row # = 5
-------------------
20
21
22
23
24
MATCH
----END-NEW-ROW----
:: input row(s) = 6
:: output row # = 6
-------------------
26
27
28
29
30
MATCH
----END-NEW-ROW----
:: input row(s) = 6
:: output row # = 7
-------------------
32
33
34
35
36
MATCH
----END-NEW-ROW----
:: input row(s) = 6
:: output row # = 8
-------------------
38
39
40
41
42
MATCH
----END-NEW-ROW----
:: input row(s) = 6
:: output row # = 9
-------------------
44
45
46
47
48
MATCH
----END-NEW-ROW----
:: input row(s) = 5
:: output row # = 10
-------------------
50
51
52
53
MATCH
----END-NEW-ROW----