Replacing a word

Shell Programming and Scripting
1

Dear Friends,
I am facing some problem with some hundred files. Hence to use these file I have to make a small change in each file. But its not possible to open each file and make changes manually. Hence I need guidance frm you to automate it.

Example File name is "Queue_11.txt"

reload sec=F
Code=7
reload sec=F
reload sec=F
No-load=F1
Reset
NULL
A-cap=LA
reload sec=F

In above text I want to replace reload sec=F to reload sec=FQ. But occurrence of this pattern is around 4 times in whole file... I want to replace only 3rd line.

I am expecting o/p as follows
reload sec=F
Code=7
reload sec=F
reload sec=FQ
No-load=F1
Reset
NULL
A-cap=LA
reload sec=F

Please suggest.

2 
awk '3==c++ && /^reload sec=F$/{$0=$0"Q"}1' infile > newfile
3

If the line you want to change is the 4th line in each file:

$ ls
queue_11.txt  queue_12.txt	 queue_13.txt

$ ls Que*.txt |
> while read FILE
> do
> sed '4s/F/FQ/' ${FILE} > ${FILE}.new
> done

$ ls
queue_11.txt.new	queue_12.txt.new  queue_13.txt.new
queue_11.txt  queue_12.txt	queue_13.txt

$ cat Queue_11.txt.new 
reload sec=F
Code=7
reload sec=F
reload sec=FQ
No-load=F1
Reset
NULL
A-cap=LA
reload sec=F

$ cat Queue_12.txt.new
reload sec=F
Code=7
reload sec=F
reload sec=FQ
No-load=F1
Reset
NULL
A-cap=LA
reload sec=F

$ cat Queue_13.txt.new
reload sec=F
Code=7
reload sec=F
reload sec=FQ
No-load=F1
Reset
NULL
A-cap=LA
reload sec=F
4 
sed  '3s/reload sec=F/reload sec=FQ/' infile > newfile

in GNU sed you can set the -i option to change your input file

5

If the pattern isn't on the 3rd line and you want to replace the 3rd occurance (wherever):

awk '/reload sec=F/ && ++c==3{$0="reload sec=FQ"}1' file > newfile
6

bash

count=0
while read -r line
do
    case "$line" in
        *"reload sec=F"* )
            count=$((count+1))
            if [ "$count" -eq 3 ] ;then
                line=${line/reload sec=F/reload sec=QF}
            fi
            ;;
    esac
    echo $line
done < "file"
7 
awk '3==c++ && /^reload sec=F$/{$0=$0"Q"}1' infile > newfile
awk '/reload sec=F/ && ++c==3{$0="reload sec=FQ"}1' file > newfile

Why have the different?