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Top Forums Shell Programming and Scripting How to read n number of lines from a file Post 302361017 by jp2542a on Monday 12th of October 2009 01:58:48 AM
Old 10-12-2009
Code:
#!/bin/bash

Assuming that the file this code is in has the executable attribute, the system will use /bin/bash to execute it.

Code:
echo "Enter file name"
read file

Reads the file name into variable 'file'

Code:
echo "Enter the number"
read n

Reads the number of lines over which the awk script will find the max.

Code:
awk -v count=$n '{k = $1; getline; for (j=1; j<cunt; j++) {if ( $1 > k ) k = $1; getline; } print k}' $file

This is the awk command to do the work.

Code:
-v count=$n

Sets the awk variable count to the number of lines to use for the comparison.

Code:
'{k = $1; getline; for (j=1; j<cunt; j++) {if ( $1 > k ) k = $1; getline; } print k}'

This is the awk program. It says:

For everyline
set k to the first value of the current input line

---------- Post updated at 10:58 PM ---------- Previous update was at 10:48 PM ----------

Code:
#!/bin/bash

Assuming that the file this code is in has the executable attribute, the system will use /bin/bash to execute it.

Code:
echo "Enter file name"
read file

Reads the file name into variable 'file'

Code:
echo "Enter the number"
read n

Reads the number of lines over which the awk script will find the max.

Code:
awk -v count=$n '{k = $1; getline; for (j=1; j<count; j++) {if ( $1 > k ) k = $1; getline; } print k}' $file

This is the awk command to do the work.

Code:
-v count=$n

Sets the awk variable count to the number of lines to use for the comparison.

Code:
'{k = $1; getline; for (j=1; j<count; j++) {if ( $1 > k ) k = $1; getline; } print k}'

This is the awk program. It says:

Code:
For every line
  set k to the first value of the current input line
  Get the next input line
  For j starting at 1, until j = count do the following
    If the new value is greater than k, set k to the new higher value
    get the next line
  End For j loop
  Print the high value for the set of lines
End For every line loop


Code:
$file

This is the name of the input file.
 

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