Read row number from 1 file and print that row of second file

Shell Programming and Scripting
1

Hi. How can I read row number from one file and print that corresponding record present at that row in another file.
eg

file1

1
3
5
7
9

file2

11111
22222
33333
44444
55555
66666
77777
88888
99999

output should contain

11111
33333
55555
77777
99999

i want to do this on files having millions of records. This is just the scenario. i am trying using awk but unable to do.

2

Are the line numbers in file1 always in sorted order as they are in your sample?

3

yes. They are in sorted order. i want output like this

line1:11111
line3:33333
line5:55555
line7:77777
line9:99999

I am trying the following code but it is partly correct

awk 'NR==FNR{a[$0]++}FNR in a {print "line"FNR":"$0}' file1 file2

i get the following output

line1:1
line3:5
line5:9
line1:11111
line3:33333
line5:55555
line7:77777
line9:99999
4

You're very close. Try:

awk 'NR==FNR{a[$0]++;next}FNR in a {print "line"FNR":"$0}' file1 file2

Note that the "++" slows down the process, but doesn't change the results. You should get the same output with:

awk 'NR==FNR{a[$0];next}FNR in a{print "line"FNR":"$0}' file1 file2