One liner to insert line in a file

Ruby
#1

Can someone help to come up with Ruby one-liner to add a line at the
beginning of a file? Basically a Ruby equivalent for following sed
example-
$ sed -i “1i $variable” file.txt

–neubyr

#2

On Sat, Jan 7, 2012 at 3:07 PM, Neubyr N. [email protected] wrote:

Can someone help to come up with Ruby one-liner to add a line at the
beginning of a file? Basically a Ruby equivalent for following sed
example-
$ sed -i “1i $variable” file.txt

What have you tried so far?

#3

Got it:
$ ruby -i -pe ‘print “First Line\n” if $.==1’ filename.txt

Thanks!

#4

On Sat, Jan 7, 2012 at 10:28 PM, Josh C. [email protected]
wrote:

Downside is it doesn’t work on multiple files since Ruby’s $. doesn’t reset
for each file (not sure why not).

If you pass multiple files on the command line, they’re combined
through ARGF into one long stream.

Gavin

#5

On Sat, Jan 7, 2012 at 1:34 AM, Neubyr N. [email protected] wrote:

Got it:
$ ruby -i -pe ‘print “First Line\n” if $.==1’ filename.txt

Thanks!

–
Posted via http://www.ruby-forum.com/.

Love this!

(btw, you can use puts instead of print "...\n")

Downside is it doesn’t work on multiple files since Ruby’s $. doesn’t
reset
for each file (not sure why not).

#6

On Sat, Jan 7, 2012 at 5:32 AM, Gavin S. [email protected]
wrote:

Yeah, I guess it’s basically awk’s NR, but it seems like there should be
something equivalent to awk’s FNR