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extract a line from a file using the line number

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Top Forums Shell Programming and Scripting extract a line from a file using the line number
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Old 01-22-2009
Head tail combo is best for large volumes
I had two files with 1.28e+06 * 2 bits of info; I wanted to plot every 256 lines for each file. I am using gnuplot.

From my experience the slowest was to use the 'every' command for gnuplot, as it would load the entire file in to memory seemingly for each tiny plot. Using sed to extract a specific line was just as slow; I found this to be because after you have extracted the part you need, the rest of the file is read for good measure.

Using the head, tail combo (which I thought I would like to avoid) is orders of magnitude faster, however, it gets slightly slower (still fastest I have tried) as you progress through the file.
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LEARN ABOUT MINIX

line

line(1)                                                            User Commands                                                           line(1)

NAME

       line - read one line

SYNOPSIS

       line

DESCRIPTION

       The  line utility copies one line (up to and including a new-line) from the standard input and writes it on the standard output. It returns
       an exit status of 1 on EOF and always prints at least a new-line. It is often used within shell files to read from the user's terminal.

EXIT STATUS

       Exit status is:

       0        Successful completion

       >0       End-of-file on input.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE         |      ATTRIBUTE VALUE        |
       +-----------------------------+-----------------------------+
       |Availability                 |SUNWcsu                      |
       +-----------------------------+-----------------------------+

SEE ALSO

       sh(1), read(2), attributes(5)

SunOS 5.10                                                          1 Feb 1995                                                             line(1)