text1
text2
Pattern1
text3
text4
Pattern1
text5
text2
text6
Pattern1
text7
text8
Pattern2
text2
text9
text10
text2
Pattern1
text11
text12
Pattern1
text13
text14
Pattern1
text15
text16
Pattern2
text1
text2
Pattern1
text3
text4
Pattern1
text5
text6
Pattern1
text7
text2
text8
Pattern2
text21
text22
I want to print ONLY
Pattern1
text7
text8
Pattern2
Pattern1
text15
text16
Pattern2
Pattern1
text7
text2
text8
Pattern2
i.e. if Pattern1 is followed by Pattern2, then print lines between Pattern1 and Pattern2. I don't want lines if Pattern1 is followed by Pattern1.
An awk command is highly appreciated.
I was trying like:
awk '/Pattern1/,/Pattern2' file \> output
but it gives all the lanes that appear between two successive Pattern1 also.
You may use this awk:
awk '
/^Pattern1$/ {s = $0 ORS; next}
s != "" {s = s $0 ORS}
/^Pattern2$/ {printf "%s", s; s = ""}
' file
Pattern1
text7
text8
Pattern2
Pattern1
text15
text16
Pattern2
Pattern1
text7
text2
text8
Pattern2
$ awk '
/Pattern1/,/Pattern2/ { # between the first start and end markers
if(/Pattern1/) # at the begin marker...
b=$0 # ... reset buffer
else
b=b ORS $0 # or keep on buffering
if(/Pattern2/) # at the end marker...
print b # ... it is time to output
}' file
head -4 of output:
Pattern1
text7
text8
Pattern2
...
Making a whole lot of assumptions about unstated requirements like whether to match to the first or last Pattern2, what to do if one or the other is missing from a file,what to do if both "patterns" occur on 1 line, etc.:
$ cat tst.awk
/Pattern1/ { f=1; rec="" }
f {
rec = rec $0 ORS
if ( /Pattern2/ ) {
printf "%s", rec
f = 0
}
}
$ awk -f tst.awk file
Pattern1
text7
text8
Pattern2
Pattern1
text15
text16
Pattern2
Pattern1
text7
text2
text8
Pattern2