I have a huge text file (~1.5GB) with numerous lines ending with ".Ends".
I need a linux oneliner (perl\ awk\ sed) to find the last place '.Ends' appear in the file and add a couple of lines before it.
I tried using tac
twice, and stumbled with my perl:
When I use:
tac ../../test | perl -pi -e 'BEGIN {$flag = 1} if ($flag==1 && /.Ends/) {$flag = 0 ; print "someline\n"}' | tac
It first prints the "someline\n" and only than prints the .Ends
The result is:
…
.Ends
someline
When I use:
tac ../../test | perl -e 'BEGIN {$flag = 1} print ; if ($flag==1 && /.Ends/) {$flag = 0 ; print "someline\n"}' | tac
It doesn’t print anything.
And when I use:
tac ../../test | perl -p -e 'BEGIN {$flag = 1} print $_ ; if ($flag==1 && /.Ends/) {$flag = 0 ; print "someline\n"}' | tac
It prints everything twice:
…
.Ends
someline
.Ends
Is there a smooth way to perform this edit?
Don't have to be with my solution direction, I'm not picky...
Bonus - if the lines can come from a different file, it would be great (but really not a must)
Edit
test input file:
gla2
fla3
dla4
rfa5
.Ends
shu
sha
she
.Ends
res
pes
ges
.Ends
--->
...
pes
ges
someline
.Ends
# * some irrelevant junk * #
Inputs:
$ cat test.dat
dla4
.Ends
she
.Ends
res
.Ends
abc
$ cat new.dat
newline 111
newline 222
One awk
idea that sticks with OP's tac | <process> | tac
approach:
$ tac test.dat | awk -v new_dat="new.dat" '1;/\.Ends/ && !(seen++) {system("tac " new_dat)}' | tac
dla4
.Ends
she
.Ends
res
newline 111
newline 222
.Ends
abc
Another awk
idea that replaces the dual tac
calls with a dual-pass of the input file:
$ awk -v new_dat="new.dat" 'FNR==NR { if ($0 ~ /\.Ends/) lastline=FNR; next} FNR==lastline { system("cat "new_dat) }; 1' test.dat test.dat
dla4
.Ends
she
.Ends
res
newline 111
newline 222
.Ends
abc
NOTES:
test.dat
)