swap lines in a file

[midge25]

Hi,

I'm hoping someone can help.

I need to cut the 2nd to last line from a file and paste it to the top of the file.

For example:

Line1
Line2
Line3
Line4

Needs to change to

Line3
Line1
Line2
Line4

Thanks in advance,
midge25

 

[dickiebird]

Are the contents of 2nd last line always the same, and are they unique to the file ? Dickie Bird
db@dickiebird.freeserve.co.uk

 

[midge25]

Dickie Bird

The contents of teh 2nd last line are always different.

Tried the following and it works but is quite slow:

export header=`tail -2 ${file_name} | head -1`
sed -n "/$header/p" ${file_name} > temp1 | sed "/$header/d" ${file_name} >> temp1

Thanks

midge25

 

[dickiebird]

Thats about what I'd have produced - But someone will have a neater,quicker solution, for sure !
Dickie Bird
db@dickiebird.freeserve.co.uk

 

[CaKiwi]

Here's one way to do it using ex

ex - file << EOF
\$-mo0
wq
EOF

CaKiwi

 

[marsd]

function swap(arra,i,m) {
tmp = arra
arra = arra[m]
arra[m] = tmp
}

function parray(array,max) {
while (i <= max) {
i++
print array
}
}

BEGIN {
print ARGV[1]
while ((getline arr[a++] < ARGV[1]) > 0) {
#print a
}
close(ARGV[1])

print &quot;First: &quot; ,arr[1], &quot;Second to last: &quot;, arr[a - 2]
swap(arr,1,(a - 2))
parray(arr,a)
}

Last try to submit this. These sites would be better hosted on *nix.

 

[marsd]

Sorry, You wanted the output bumped down a line each, so
swapping isn't the only thing you need to do.

Here is the correction:

function swap(arra,i,m) {
tmp = arra
arra = arra[m]
arra[m] = tmp
}

function bump(array,n,max,val) {
tmp = array[n + 1]
array[n + 1] = val
n++
if (n < max) {
bump(array,n,max,tmp)
}
}

function parray(array,max) {
while (i <= max) {
i++
print array
}
}


BEGIN {
#print ARGV[1]
while ((getline arr[a++] < ARGV[1]) > 0) {
#print a
}
close(ARGV[1])

print &quot;First: &quot; ,arr[1], &quot;Second to last: &quot;, arr[a - 2]
swap(arr,1,(a - 2))
bump(arr,1,(a + 1),arr[a - 2])
parray(arr,a)
}