I have a file to process with sed but I am not quite familiar with the commands with capital letters used for multi-line patterns. I use seq to test the script and I have converted it to the problem described below. The sed script and expected output are also attached. I believe the script can be written in a much better way but I am not sure how to do it.
Problem description:
Filter the output of
seq $m, where$mis a given integer. removing the \$n^{\rm th}\$ line if either \$n-2\$, \$n-1\$, \$n\$, or \$n+1\$ contains the digit \$7\$.
Sed script (together with the seq pipe, note this is GNU sed):
seq "$m"|sed ':c N;N;N;:a N;s/.*\n.*7.*\n.*\n.*\n//g;tc;P;s/^[^\n]*\n//g;ba;'
I believe setting two labels (a and c) is not necessary.
Edit: There seems to be a nicer alternative, based on the answer to Delete 5 Lines Before and 6 Liens After Pattern Match Using sed, as follows,
seq "$m"|sed 'N;/7/!{P;D};:b N;s/\n/&/3;Tb;d'
This avoids writing out a lot of N; and \n's explicitly. Still I believe it can be improved.
Sample output for m=100
1
2
3
4
5
10
11
12
13
14
15
20
21
22
23
24
25
30
31
32
33
34
35
40
41
42
43
44
45
50
51
52
53
54
55
60
61
62
63
64
65
82
83
84
85
90
91
92
93
94
95
100
