How to generate a 10000 lines test file from original file with 10 lines?

Question

I want to test an application with a file containing 10000 lines of records (plus header and footer lines). I have a test file with 10 lines now, so I want to duplicate these line 1000 times. I don't want to create a C# code in my app to generate that file (is only for test), so I am looking for a different and simple way to do that.

What kind of tool can I use to do that? CMD? Visual Studio/VS Code extension? Any thought?

Use your shell, even CMD has a loop. Or do 10 copies, each doubling the file, which gives you 1024 times. — the busybee, Apr 29 '22 at 09:50

collapsar · Accepted Answer · 2022-04-29T10:01:32.087

If your data is textual, load the 10 records from your test file into an editor. Select all, copy, insert at the end of file. Repeat until the file is of length 10000+

This procedure requires ceil(log_2(1000)) cycles, 10 in your case, in general ceil(log_2(<target_number_of_lines>/<base_number_of_lines>)).

Alternative (large files)

Modern editors should not have performance problems here. However, the principle can be applied using a cat cli command. Assuming that you copy the original file into a file named dup0.txt proceed as follows:

cat dup0.txt dup0.txt >dup1.txt
cat dup1.txt dup1.txt >dup0.txt

leaving you with the quadrupled number of lines in dup0.txt.

Thank you for your answer, I did that with my text editor, like you said, copying all and appending at the end of file. — Guillermo Espert, Apr 29 '22 at 10:13

How to generate a 10000 lines test file from original file with 10 lines?

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