Shell Programming and Scripting

#!/bin/sh

line=4

awk -v var="$line" 'NR==var {
  s=$0
  getline;s=$0"\n"s
  getline;print;print s
  next
}1' fileko.tx

this is line5
this is line6
this is line7
this is line8
this is line1
this is line2
this is line3
this is line4
this is line9
this is line10
this is line11

awk -vLNO=4 'NR<=LNO {TMP[NR]=$0;next} 1; NR==LNO*2 {for (i=1; i<=LNO; i++) print TMP[i]}' file
5
6
7
8
1
2
3
4
9
10

 awk '{if(NR==1 || NR==2 || NR==3 || NR==4){A=A?A ORS $0:$0;next};if(NR==8){print $0 ORS A;} else {print}}'  Input_file

this is line5
this is line6
this is line7
this is line8
this is line1
this is line2
this is line3
this is line4
this is line9
this is line10
this is line11

awk -vLNO=4 '                                   # supply desired line count into LNO variable
NR<=LNO         {TMP[NR]=$0;next}               # rows up to LNO stored in TMP array, don''t print
1                                               # default action: print
NR==LNO*2       {for (i=1; i<=LNO; i++)         # print the TMP array after another LNO rows (assumption, not specified)
                        print TMP[i]}
' file

 awk '{if(NR==1 || NR==2 || NR==3 || NR==4){A=A?A ORS $0:$0;next};if(NR==8){print $0 ORS A;} else {print}}'  Input_file
 if(NR==1 || NR==2 || NR==3 || NR==4)  #### Looking for condition if line number is equal to 1 or 2 or 3 or 4
{A=A?A ORS $0:$0;next}                          #### If above condition is TRUE then I am creating a variable which will hold the 
 current line's value with it's previouls value character ? is to perform a action when condition before will be TRUE and : is used to perform action when condition is FALSE.
next                                                         #### After above variable's creation leave next statements and move next
 if(NR==8)                                               #### Looking for condition when line number is 8
{print $0 ORS A;}                                    #### if above condition is TRUE then print the 8th line and print variable A, which has now value of lines from 1 to 4 in it
else                                                         #### Apart of any line pther than 8 it will do simple print operation.

#!/usr/bin/env bash

# @(#) s1	Demonstrate move lines with line editor, ed.

# Infrastructure: scaffolding, functions, debugging, identification, etc.
LC_ALL=C ; LANG=C ; export LC_ALL LANG
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C ed

FILE=${1-data1}
cp sacred $FILE

pl " Input data file $FILE:"
cat $FILE

pl " Results:"
ed $FILE 2>/dev/null <<EOF
1,4m8
w
q
EOF
cat $FILE

exit 0

$ ./s1

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian 5.0.8 (lenny, workstation) 
bash GNU bash 3.2.39
ed GNU Ed 0.7

-----
 Input data file data1:
1
2
3
4
5
6
7
8
9
10

-----
 Results:
5
6
7
8
1
2
3
4
9
10