I have a file with data extracted, and need to insert a header with a constant string, say: H|PayerDataExtract

if i use sed, i have to redirect the output to a seperate file like

sed ' sed commands' ExtractDataFile.dat > ExtractDataFileWithHeader.dat

the same is true for awk

and in its simplist form i could say
echo 'H|PayerDataExtract' > ExtractDataFileWithHeader.dat
cat ExtractDataFile.dat >> ExtractDataFileWithHeader.dat
mv ExtractDataFileWithHeader.dat ExtractDataFile.dat

but in all of the above an extra file is created. If i were to do this in vi manually the extra file could be avoided.

Is there a way to avoid the extra file while still not having to manually use vi in a interactive manner? This is even more neccessary if the file uses over 50% filespace and an extra file will just double my usage , though temporarily

This is crazy, I agree.

Typically, in situations like this, I employ an "original_file_name.info" file instead.

In the .info file I'll put all the information necessary for another program/user
to verify the contents of the huge file i created.

There are other options . . . . like creating a dummy header record in
the file creation program . . . and then using fseek() to hop back to
the beginning and overwrite the header info....

but you may not have this much control over how this file is created.

There are 'edit in place' features for GNU sed and for perl (perl -pie ' perl script here').
However they do use tmp files behind the scenes

You can even use the sed 'insert' command along with -i (inline) option to place the the "header" at a specific line number (like line 1).

Something like this should work:

sed -i '1 i \Some Header Text Here' ExtractDataFile.dat

Why not create an ed script instead? And then use 'patch'? But that would still require a temp file in the background though you wouldn't notice.

hi ddreggors/jim

i tried this - and it fails with the below error

sed -i '1 i \HeaderText' ExtractDataFile.txt
sed: illegal option -- i

The system is a SunOS ussun1l 5.8 Generic_117350-60 sun4u sparc SUNW,Sun-Fire-15000

the perl option is out for me as the client may not want to install any piece of software without business cause, however as long as the tmp file is created in the /tmp space and not my file-dir i think i'm ok - any more ideas anyone?

try this:

sed 1'i\HeaderText' ExtractDataFile.txt

sed -i 1'i\HeaderText' ExtractDataFile.txt