topic Re: insert text before first line in Operating System - HP-UX

insert text before first line

Anand_30 — Wed, 14 Jul 2004 20:43:29 GMT

Hi,

I am working on Sun OS. I need to enter a text before the first line in a file. How would i accomplish the task using sed.

Thanks,
Andy

Re: insert text before first line

Geoff Wild — Wed, 14 Jul 2004 21:04:12 GMT

sed -e '1i\ ' filename

Rgds...Geoff

Re: insert text before first line

Hein van den Heuvel — Wed, 14 Jul 2004 21:29:51 GMT

Isn't it a little more tricky to get the newline there?

sed -e '1i\^Jtest^J' file > newfile

In this example the ^J stands for a linefeed.
You can enter this on the command line with a control-V followed by control-J

Alternative using replace instead of insert:

sed '1s/^/test\^J/' file > newfile

Again ^J is entered as control-v followed by control-j and a \ is needed to escape that.

You may want to check out the "Handy one-liners for SED" file. For example the one attached to:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=630972

hein.

Re: insert text before first line

Abdul Rahiman — Wed, 14 Jul 2004 21:37:22 GMT

Iam having fun with inserting ^v-^J ;-)
Or make use of a simple script,
# cat a.sed
1i\
mytext

# sed -f a.sed myfile > newfile

regds,
Abdul.

Re: insert text before first line

Hein van den Heuvel — Wed, 14 Jul 2004 21:51:45 GMT

I forgot to put in an obligatory perl alternative:

perl -e '@_=<>; print "test\n",@_' x

Here we tell perl to 'slurp' the input into an array @_, print the new line, and burp the array out again. This may be useful for more elaborated problems.

And just with the shell..

echo "test" > newfile; cat file >> newfile

Hein.

Re: insert text before first line

Hein van den Heuvel — Wed, 14 Jul 2004 22:16:58 GMT

[too bad we can not edit replies]

before someone else comments, yes I know 'slurpling' in perl is not efficient and does not scale well for large files.
Same goes for sed.
The more efficient processing for large files is just read and write in a loop.

perl -pe '$i++||print "test\n"' file > newfile

Hein.

Re: insert text before first line

Muthukumar_5 — Wed, 14 Jul 2004 23:43:54 GMT

hai,

We can do it with sed as,
cat /input file/ | sed -e '1 s/^/\
/g' > netoutput file

or we can simply do it without sed using temporary files as,

cat input-file /tmp/testfile.log
echo "" > inputfile
cat /tmp/testfile.log >> inputfile

Regards,
Muthukumar.