[Linux] Caution: using command 'less' on gzipped file

A couple of years ago, I found that I can use Linux command less to view gzipped file, such as:

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less in.gz

This is very convenient to view gzipped file content.

However, recently, I noticed a problem with it. For a file which has 42196516 lines, if I opened it with less, it gave me a count of 30356021 lines:

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less test.fq.gz | wc -l; # giving 30356021
gzip -dc test.fq.gz | wc -l; # giving 42196516

Therefore, gzip -dc gives correct answer while less truncates the input stream.

In conclusion, for safety, always use gzip, other than less, to open gzipped files.

Last modified on 2019-12-27