Inserting text at the beginning of a file with sed via the terminal in Linux [duplicate]

Question

Possible Duplicate:
How can I prepend a tag to the beginning of several files?

How do I insert text at the beginning of a file via terminal?

Answer 1

sed is for editing streams -- a file is not a stream. Use a program that is meant for this purpose, likeed or ex. The -i option to sed is not only not portable, it will also break any symlinks to your file, since it essentially deletes it and recreates it, which is pointless.

ed -s file << EOF
0a
some text
you want to insert
goes here
.
w
EOF

Answer 2

Specify a line range in input file which is restricted to first line, then replace beginning of line with text to add and redirect o/p to a new file

cat f1
one

sed '1,1 s/^/abcdef\n/' < f1 >f2

cat f2
abcdef
one

Answer 3

+1 for abc's answer because I find his nice sed expression.

However Regis doesn't want two files, he wants to insert text in his file; so I have adapted abc's answer:

hmontoliu@ulises:/tmp$ cat >  f1 
one
^C
hmontoliu@ulises:/tmp$ sed -i '1 s/^/foobar\n/' f1
hmontoliu@ulises:/tmp$ cat f1
foobar
one