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Swapping or switching 2 lines using sed

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Top Forums Shell Programming and Scripting Swapping or switching 2 lines using sed
# 22  
Old 11-16-2008
Quote:
Originally Posted by null7
Sorry if this question is annoying you. Smilie
Not at all, because you're right. I've correct the code, if you have any question don't hestitate to ask.

Code:
#!/bin/sh

line=3
line1=9

awk -v var="$line" -v var1="$line1" 'NR==var {
  s=$0
  for(i=var+1;i<var1;i++){
    getline;s1=s1?s1 "\n" $0:$0
  }
  getline;print;print s1 "\n" s
  next
}1' file

Regards
# 23  
Old 11-16-2008
And another one:

Code:
awk 'NR == l1, NR == l2 {
  _[NR] = $0
  if (NR == l2) {
    print
    for (i=l1+1; i<l2; i++)
      print _[i]
    print _[l1]
    }
  next
  }1' l1=3 l2=9 infile

# 24  
Old 11-18-2008
Quote:
Originally Posted by Franklin52
Not at all, because you're right. I've correct the code, if you have any question don't hestitate to ask.

Code:
#!/bin/sh

line=3
line1=9

awk -v var="$line" -v var1="$line1" 'NR==var {
  s=$0
  for(i=var+1;i<var1;i++){
    getline;s1=s1?s1 "\n" $0:$0
  }
  getline;print;print s1 "\n" s
  next
}1' file

Regards
Thanx and its work. but can u explain me this line:
Code:
s1=s1?s1 "\n" $0:$0

I know its C conditional and the output pattern but didn't get the meaning. I tried print line by line to see the output. What i got was,

1st loop:
Code:
before getline, s1:$0:3
after getline, s1:$0:4
after s1=s1?s1 "\n" $0:$0, 4

2nd loop:
Code:
before getline, s1:4$0:4
after getline, s1:4$0:5
after s1=s1?s1 "\n" $0:$0, 
4
5

3rd loop:
Code:
before getline, s1:
4
5$0:5
 after getline,s1:
4
5$0:6
 after s1=s1?s1 "\n" $0:$0, 
4
5
6

# 25  
Old 11-19-2008
Hi,

Code:
s1=s1?s1 "\n" $0:$0

This is a conditional expression operator. The format is : condition ? expression1 : expression2.
If the condition is true, the result is expression1 else the result is expression2.

With our command we check the value of s1 (s1?). If s1 is true (s1 is not empty) we assign the contents of s1, a newline ("\n") and the current record ($0) to s1. If the condition is false (s1 is empty) we assign the current record ($0) to s1.

Regards
# 26  
Old 11-19-2008
hi

below sed should be ok for you


Code:
sed -n '3 !{
p
}
3 {
h
n
x
H
n
x
H
x
p
}' file

# 27  
Old 11-19-2008
Quote:
Originally Posted by Franklin52
Hi,

Code:
s1=s1?s1 "\n" $0:$0

This is a conditional expression operator. The format is : condition ? expression1 : expression2.
If the condition is true, the result is expression1 else the result is expression2.

With our command we check the value of s1 (s1?). If s1 is true (s1 is not empty) we assign the contents of s1, a newline ("\n") and the current record ($0) to s1. If the condition is false (s1 is empty) we assign the current record ($0) to s1.

Regards
Owh..thank you. you opened my eyes. too many thing is mind, and i didn't realize it. didn't realize "\n" $0 statement is expression1. phewhh..Smilie thanx again.

radoulov/summer_cherry,
Appreciate your feedback but yet to try. Smilie Thanx.

Btw, i don't know whether I can post this question here. Seems it related to this swapping, i think i can post it here. Sorry if not.

Let's say I've files named file1, file2, file3 and so on.
Each file contain the same format.
What I'm working now is i'm trying to swap line 2 and line 3 for each file(success with previous code)
but there is condition where the 2nd line must contains specific string, let say: 1012345678. To simplyfy, the string is in column 4.
If 2nd line of the file does not contain the specified string, the script do nothing.

My Algorithm:
Code:
if (line==2 && column 4 == 1021436587)
{
    backup the original file (yet to get the solution)
    swap the line
}
else (optional)
{
    don't do anything
}

Code:
#!/bin/sh

ls file* > list
for i in `cat list`
do

awk '{ if ((NR==2) && ( $4 == 1012345678))
    {
        nawk -v var="$line" -v var1="$line1" 'NR==var 
        {
            s=$0
            for(i=var+1;i<var1;i++)
            {
                #print "yyyyy " "s1:" s1 "$0:" $0 " yyyyy"
                getline;
                #print "xxxxx " "s1:" s1 "$0:" $0 " xxxxx"
                s1=s1?s1 "\n" $0:$0
                #print "zzzzz " s1 " zzzzz"
            }
                getline;print;print s1 "\n" s
                next
        }1' $i
     } else 
     {
        print "do nothing"
     }
       }' $i
done

Eg input file1:
Code:
header
abc  def   ghi   1012345678       500010.00                       
abc  def   ghi   2022222222             10.00 
abc  def   ghi   1022222222             10.00                       
abc  def   ghi   2012345678       500010.00

output:
Code:
header
abc  def   ghi   2022222222             10.00
abc  def   ghi   1012345678       500010.00                                          
abc  def   ghi   1022222222             10.00
abc  def   ghi   2012345678       500010.00

I have problem to get it right. Hopefully i can get suggestion/advise/solution from you guys. Smilie

Rgrds.
# 28  
Old 11-19-2008
To swap the 2nd and the 3th line:

Code:
awk 'NR==2 && $4 == "1021436587" {
  s=$0;getline;print $0; print s;next
}
{print}' file > outfile

Explanation:

If linenumber = 2 and field 4 is "1021436587":
1. put the contents of the record to the string s.
2. get the next line.
3. print the line
4. print the previous line
5. get the next record.

The next statement reads the next line and the passes controle back to the first line of the script while the getline function goes further with the next command.

Btw, in the output of your example you've swapped the 1st and the 2nd line.

Regards
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