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bashshellunixawksed

Bash tool to get nth line from a file

Is there a "canonical" way of doing that? I've been using head -n | tail -1 which does the trick, but I've been wondering if there's a Bash tool that specifically extracts a line (or a range of lines) from a file.

By "canonical" I mean a program whose main function is doing that.

Solution

  • head and pipe with tail will be slow for a huge file. I would suggest sed like this:

    sed 'NUMq;d' file

    Where NUM is the number of the line you want to print; so, for example, sed '10q;d' file to print the 10th line of file.

    Explanation:

    NUMq will quit immediately when the line number is NUM.

    d will delete the line instead of printing it; this is inhibited on the last line because the q causes the rest of the script to be skipped when quitting.

    If you have NUM in a variable, you will want to use double quotes instead of single:

    sed "${NUM}q;d" file