I have a program that might want to estimate completion on large files. Any thoughts on the best way to quickly estimate the line count in a very large text file? My idea was to get the file size, and if it's less than 100MB just use wc -l. Otherwise take 100 4 KiB (aligned) samples by seeking to pre-calculated offsets in the file and reading 4096 bytes, counting the number of bytes between each newline and taking that as the line length; then the number of lines is $filesize / ($avg_line_len + length("\n")).

Update: replaced "seeking through" with "seeking to pre-calculated offsets in"

In reply to Estimate line count in text file by xaprb

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