Python insert a line just above the second occurrence of a pattern from end of file [closed]

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0
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I have a RHEL kickstart file as below with multiple %post ... %end sections in it having many lines of Python code in between them.

%post
.....
.....
%end
%post
.....
.....
%end
%post
.....
.....
%end

I am trying to insert a new line with some data just before (above) the 2nd occurrence of search pattern "%end" from last (EOF). Any hints/input is really appreciated.

edited May 10 at 6:08

asked May 9 at 12:43

Ibrahim Quraish

1419

closed as unclear what you're asking by Jeff Schaller, Jesse_b, roaima, G-Man, nwildner May 10 at 17:05

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, itÃ¢Â€Â™s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

how about Unix command-line tools?
â€“Â RomanPerekhrest
May 9 at 13:20

@don_crissti I tried with findall() but gives list of the patterns from that I have used -2 index to retrieve the 2nd occurrence of pattern from last, but unable to fetch the line no above this 2nd occurrence of the pattern
â€“Â Ibrahim Quraish
May 9 at 14:24

@RomanPerekhrest, I used the code something like, tac file | awk -v n=0 '/%end/ n++; if (n==3) print FNR-1'
â€“Â Ibrahim Quraish
May 9 at 14:26

What's the relevance of Python in the title?
â€“Â roaima
May 9 at 22:21

@roaima I have to do it via Python to insert some python code into this target kickstart file which contains python code. I am thinking of using shell script is to be imbibed in Python's subprocess.Popen()
â€“Â Ibrahim Quraish
May 10 at 6:08

Â |Â
show 1 more comment

up vote
0
down vote

favorite

I have a RHEL kickstart file as below with multiple %post ... %end sections in it having many lines of Python code in between them.

%post
.....
.....
%end
%post
.....
.....
%end
%post
.....
.....
%end

I am trying to insert a new line with some data just before (above) the 2nd occurrence of search pattern "%end" from last (EOF). Any hints/input is really appreciated.

edited May 10 at 6:08

asked May 9 at 12:43

Ibrahim Quraish

1419

closed as unclear what you're asking by Jeff Schaller, Jesse_b, roaima, G-Man, nwildner May 10 at 17:05

how about Unix command-line tools?
â€“Â RomanPerekhrest
May 9 at 13:20

@don_crissti I tried with findall() but gives list of the patterns from that I have used -2 index to retrieve the 2nd occurrence of pattern from last, but unable to fetch the line no above this 2nd occurrence of the pattern
â€“Â Ibrahim Quraish
May 9 at 14:24

@RomanPerekhrest, I used the code something like, tac file | awk -v n=0 '/%end/ n++; if (n==3) print FNR-1'
â€“Â Ibrahim Quraish
May 9 at 14:26

What's the relevance of Python in the title?
â€“Â roaima
May 9 at 22:21

@roaima I have to do it via Python to insert some python code into this target kickstart file which contains python code. I am thinking of using shell script is to be imbibed in Python's subprocess.Popen()
â€“Â Ibrahim Quraish
May 10 at 6:08

Â |Â
show 1 more comment

up vote
0
down vote

favorite

I have a RHEL kickstart file as below with multiple %post ... %end sections in it having many lines of Python code in between them.

%post
.....
.....
%end
%post
.....
.....
%end
%post
.....
.....
%end

I am trying to insert a new line with some data just before (above) the 2nd occurrence of search pattern "%end" from last (EOF). Any hints/input is really appreciated.

edited May 10 at 6:08

asked May 9 at 12:43

Ibrahim Quraish

1419

I have a RHEL kickstart file as below with multiple %post ... %end sections in it having many lines of Python code in between them.

%post
.....
.....
%end
%post
.....
.....
%end
%post
.....
.....
%end

I am trying to insert a new line with some data just before (above) the 2nd occurrence of search pattern "%end" from last (EOF). Any hints/input is really appreciated.

edited May 10 at 6:08

asked May 9 at 12:43

Ibrahim Quraish

1419

edited May 10 at 6:08

asked May 9 at 12:43

Ibrahim Quraish

1419

asked May 9 at 12:43

Ibrahim Quraish

1419

asked May 9 at 12:43

Ibrahim Quraish

1419

closed as unclear what you're asking by Jeff Schaller, Jesse_b, roaima, G-Man, nwildner May 10 at 17:05

how about Unix command-line tools?
â€“Â RomanPerekhrest
May 9 at 13:20

@don_crissti I tried with findall() but gives list of the patterns from that I have used -2 index to retrieve the 2nd occurrence of pattern from last, but unable to fetch the line no above this 2nd occurrence of the pattern
â€“Â Ibrahim Quraish
May 9 at 14:24

@RomanPerekhrest, I used the code something like, tac file | awk -v n=0 '/%end/ n++; if (n==3) print FNR-1'
â€“Â Ibrahim Quraish
May 9 at 14:26

What's the relevance of Python in the title?
â€“Â roaima
May 9 at 22:21

@roaima I have to do it via Python to insert some python code into this target kickstart file which contains python code. I am thinking of using shell script is to be imbibed in Python's subprocess.Popen()
â€“Â Ibrahim Quraish
May 10 at 6:08

Â |Â
show 1 more comment

how about Unix command-line tools?
â€“Â RomanPerekhrest
May 9 at 13:20

@don_crissti I tried with findall() but gives list of the patterns from that I have used -2 index to retrieve the 2nd occurrence of pattern from last, but unable to fetch the line no above this 2nd occurrence of the pattern
â€“Â Ibrahim Quraish
May 9 at 14:24

@RomanPerekhrest, I used the code something like, tac file | awk -v n=0 '/%end/ n++; if (n==3) print FNR-1'
â€“Â Ibrahim Quraish
May 9 at 14:26

What's the relevance of Python in the title?
â€“Â roaima
May 9 at 22:21

@roaima I have to do it via Python to insert some python code into this target kickstart file which contains python code. I am thinking of using shell script is to be imbibed in Python's subprocess.Popen()
â€“Â Ibrahim Quraish
May 10 at 6:08

how about Unix command-line tools?
â€“Â RomanPerekhrest
May 9 at 13:20

@don_crissti I tried with findall() but gives list of the patterns from that I have used -2 index to retrieve the 2nd occurrence of pattern from last, but unable to fetch the line no above this 2nd occurrence of the pattern
â€“Â Ibrahim Quraish
May 9 at 14:24

@RomanPerekhrest, I used the code something like, tac file | awk -v n=0 '/%end/ n++; if (n==3) print FNR-1'
â€“Â Ibrahim Quraish
May 9 at 14:26

What's the relevance of Python in the title?
â€“Â roaima
May 9 at 22:21

@roaima I have to do it via Python to insert some python code into this target kickstart file which contains python code. I am thinking of using shell script is to be imbibed in Python's subprocess.Popen()
â€“Â Ibrahim Quraish
May 10 at 6:08

Â |Â
show 1 more comment

2 Answers
2

active

oldest

votes

up vote
1
down vote

accepted

Python snippet that inserts text spam at the last position in the second-to-last %post..%end block:

with open('input') as fp:
 lines = fp.readlines()

locs = [i for i, val in enumerate(lines) if val == '%endn']
lines.insert(locs[-2], 'spam' + 'n')

with open('input', 'w') as fp:
 fp.write(''.join(lines))

answered May 9 at 15:58

hoefling

418410

add a commentÂ |Â

up vote
1
down vote

To insert "some data" before next to last pattern line.
grep + awk solution:

awk -v n="$(($(grep -c '^%end' inputfile) - 1))" 
'/^%end/ if (++cnt == n) print "some data" 1' inputfile

The output:

%post
.....
.....
%end
%post
.....
.....
some data
%end
%post
.....
.....
%end

answered May 9 at 15:25

RomanPerekhrest

22.4k12144

add a commentÂ |Â

2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

up vote
1
down vote

accepted

Python snippet that inserts text spam at the last position in the second-to-last %post..%end block:

with open('input') as fp:
 lines = fp.readlines()

locs = [i for i, val in enumerate(lines) if val == '%endn']
lines.insert(locs[-2], 'spam' + 'n')

with open('input', 'w') as fp:
 fp.write(''.join(lines))

answered May 9 at 15:58

hoefling

418410

add a commentÂ |Â

up vote
1
down vote

accepted

Python snippet that inserts text spam at the last position in the second-to-last %post..%end block:

with open('input') as fp:
 lines = fp.readlines()

locs = [i for i, val in enumerate(lines) if val == '%endn']
lines.insert(locs[-2], 'spam' + 'n')

with open('input', 'w') as fp:
 fp.write(''.join(lines))

answered May 9 at 15:58

hoefling

418410

add a commentÂ |Â

up vote
1
down vote

accepted

Python snippet that inserts text spam at the last position in the second-to-last %post..%end block:

with open('input') as fp:
 lines = fp.readlines()

locs = [i for i, val in enumerate(lines) if val == '%endn']
lines.insert(locs[-2], 'spam' + 'n')

with open('input', 'w') as fp:
 fp.write(''.join(lines))

answered May 9 at 15:58

hoefling

418410

Python snippet that inserts text spam at the last position in the second-to-last %post..%end block:

with open('input') as fp:
 lines = fp.readlines()

locs = [i for i, val in enumerate(lines) if val == '%endn']
lines.insert(locs[-2], 'spam' + 'n')

with open('input', 'w') as fp:
 fp.write(''.join(lines))

answered May 9 at 15:58

hoefling

418410

answered May 9 at 15:58

hoefling

418410

answered May 9 at 15:58

hoefling

418410

answered May 9 at 15:58

hoefling

418410

add a commentÂ |Â

up vote
1
down vote

To insert "some data" before next to last pattern line.
grep + awk solution:

awk -v n="$(($(grep -c '^%end' inputfile) - 1))" 
'/^%end/ if (++cnt == n) print "some data" 1' inputfile

The output:

%post
.....
.....
%end
%post
.....
.....
some data
%end
%post
.....
.....
%end

answered May 9 at 15:25

RomanPerekhrest

22.4k12144

add a commentÂ |Â

up vote
1
down vote

To insert "some data" before next to last pattern line.
grep + awk solution:

awk -v n="$(($(grep -c '^%end' inputfile) - 1))" 
'/^%end/ if (++cnt == n) print "some data" 1' inputfile

The output:

%post
.....
.....
%end
%post
.....
.....
some data
%end
%post
.....
.....
%end

answered May 9 at 15:25

RomanPerekhrest

22.4k12144

add a commentÂ |Â

up vote
1
down vote

To insert "some data" before next to last pattern line.
grep + awk solution:

awk -v n="$(($(grep -c '^%end' inputfile) - 1))" 
'/^%end/ if (++cnt == n) print "some data" 1' inputfile

The output:

%post
.....
.....
%end
%post
.....
.....
some data
%end
%post
.....
.....
%end

answered May 9 at 15:25

RomanPerekhrest

22.4k12144

To insert "some data" before next to last pattern line.
grep + awk solution:

awk -v n="$(($(grep -c '^%end' inputfile) - 1))" 
'/^%end/ if (++cnt == n) print "some data" 1' inputfile

The output:

%post
.....
.....
%end
%post
.....
.....
some data
%end
%post
.....
.....
%end

answered May 9 at 15:25

RomanPerekhrest

22.4k12144

answered May 9 at 15:25

RomanPerekhrest

22.4k12144

answered May 9 at 15:25

RomanPerekhrest

22.4k12144

answered May 9 at 15:25

RomanPerekhrest

22.4k12144

add a commentÂ |Â

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