Dear All,

I have text file like this:

Header
Record 1
Record 2
.......
Record n
Tail

This line of code :
awk '{ if ( NR == 1 ) { head=substr($0,1,300);} else { last = substr($0,1,300);}END{printf "Header is : %-300s Trailer is : %-300s\n", head, last}' filename

converted Header and Trailer in one line and within 300 character each.The output is just one line.

Now I want to overwrite this one line above (Header+ Tail) over the first line of original file (orginal header) and delete the Tail........i can copy this header and tail to new file and then append Record 1 to Record n to this new file, but that will cause too low performance........so I think better to update first and the last line of the this file.................so how can i do that?

i.e. 1-update the header with new line i.e. (header+trailer)
2-delete the tail in original file (may be using cut tail -1 filename?)

Dont bump up your issue by opening a new thread. You can address it in your old thread

Header and Footer

Save the output from the awk into a variable like

And then you can do something like

Thanks.....I tried the code but sed command is not working properly,it is giving output:

sed: command garbled: 1 c\ Header is: Headervalue.......Trailer is: Trailer value.....


It makes no change in the file as well.

any luck for me as well?

There has been another thread as lorcan said and this seems to be only a continuation of the above thread in a new post.

Please continue to post your question in the same thread so that it would be easier to follow up rather than starting a new thread for the same question.

Assuming I have understood your requirement try this,

combined header and trailer is available followed by that
header is available
all the records are displayed
trailer record is not displayed

If this is not what you had asked for, let us know

To print the Header and trailer in one line with 300 char each. Removal of header and trailer line. Use the below

Just a flavour to matrixmadhan's command as per your req