Getting every nth line from file

I had a problem recently where I wanted to extract every 5th line from file and I knew that every 10 lines data points to same 10 keys


awk 'NR%5 == 0' file.txt

gave me that




In general if we want to extract every nth line from  file with repeated section of length L

we can just do




awk 'NR%L == n' file.txt 



Assume that we have lines with every section of 5 lines 
awk 'NR%5 == 1' values | awk '{n += $1}; END{print n}'   # sum of every 1st line
awk 'NR%5 == 2' values | awk '{n += $1}; END{print n}'   # sum of every 2nd line
awk 'NR%5 == 3' values | awk '{n += $1}; END{print n}'   # sum of every 3rd line
awk 'NR%5 == 4' values | awk '{n += $1}; END{print n}'   # sum of every 4th line
awk 'NR%5 == 0' values | awk '{n += $1}; END{print n}'   # sum of every 5th line

How to prepend text to all files in a directory

find  ./ -type f | xargs sed -i '1i wget https://repo.continuum.io/archive/Anaconda3-5.1.0-Linux-x86_64.sh \
chmod +x Anaconda3-5.1.0-Linux-x86_64.sh \
./Anaconda3-5.1.0-Linux-x86_64.sh -b  \
source ~/.bashrc' $1



find ./ -type f   #Give all the files
xargs  # run thefollowing command
$1 #will be the file path

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