Shell Programming and Scripting

This is just my idea.
------------cut here------------
#!/bin/ksh

echo "Enter No.of lines to remove from TOP : "
read top
echo "Enter No.of lines to remove from BOTTOM :"
read bottom
echo "Enter the file name:"
read fn

tot=`wc -l < $fn`
rmtop=`expr $tot - $top`
rmtail=`expr $tot - $bottom`

echo "Total lines"
echo "-----------"
cat $fn
echo "=================================================================================="
echo "Removing of last $bottom lines"
echo "------------------------------"
cat $fn|head -$rmtop
echo "=================================================================================="
echo "Removing of first $top lines"
echo "----------------------------"
cat $fn|tail -$rmtail
------------------Cut here-------------------------------
----------------------------------------------------------------
Out Put:-
---------
# sh test2.sh
Enter No.of lines to remove from TOP :
4
Enter No.of lines to remove from BOTTOM :
4
Enter the file name:
/venkat/scripts/file3
Total lines
-----------
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
==================================================================================
Removing of last 4 lines
------------------------------
1
2
3
4
5
6
7
8
9
10
11
==================================================================================
Removing of first 4 lines
----------------------------
5
6
7
8
9
10
11
12
13
14
15
#

Code:

 $ S=`awk 'END {print NR-4}' file.tmp`; sed -e '1,5 d' -e "$S,$ d" file.tmp > file.tmp.tmp ; mv file.tmp.tmp file.tmp

This would never be possible to read the contents without opening the file.

Be it any file reading utility like sed, awk, vi internally fopen is executed.

Did you mean not opening the file in an editor ?

hi,

to delete first 5 lines use:
tail +6 input.dat > output.dat

remember that +(x+1) if you want to delete first x lines.

baloo