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Full Discussion: Use sed to print first n lines and last n lines of an output.
Top Forums Shell Programming and Scripting Use sed to print first n lines and last n lines of an output. Post 302838957 by Don Cragun on Wednesday 31st of July 2013 01:43:40 AM
Old 07-31-2013
I know that you asked for a sed solution, but ed is well suited to something like this and only needs to be invoked once to do it. This was tested using a Korn shell, but will work with any shell that recognizes basic Bourne shell syntax:
Code:
#!/bin/ksh
# Usage: tester file count
ed -s "$1" <<-EOF
        1,$2p
        \$-$2+,\$p
        q
EOF

If you save this in a file named tester, make it executable with:
Code:
chmod +x tester

and run it with:
Code:
./tester a.txt 1

where a.txt contains the text shown in the 3rd message in this thread, the output will be:
Code:
1
7

and the output from the command:
Code:
./tester a.txt 5

will be:
Code:
1
2
3
4
5
3
4
5
6
7

These 2 Users Gave Thanks to Don Cragun For This Post:
carloszhang krishmaths
 

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LEARN ABOUT OPENDARWIN

suspend

suspend(1)							   User Commands							suspend(1)

NAME

       suspend - shell built-in function to halt the current shell

SYNOPSIS

   sh
       suspend

   csh
       suspend

   ksh
       suspend

DESCRIPTION

   sh
       Stops the execution of the current shell (but not if it is the login shell).

   csh
       Stop the shell in its tracks, much as if it had been sent a stop signal with ^Z. This is most often used to stop shells started by su.

   ksh
       Stops the execution of the current shell (but not if it is the login shell).

ATTRIBUTES

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

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

SEE ALSO

       csh(1), kill(1), ksh(1), sh(1), su(1M), attributes(5)

SunOS 5.10							    15 Apr 1994 							suspend(1)
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