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Insert at the beginning of odd lines

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# 1  
Old 09-10-2012
Insert at the beginning of odd lines
Hello people,

I am trying with sed to insert some text at the beginning of each odd line of a file but no luck. Can you please help. Awk is also suitable but I am not very familiar with it.

Thank you in advance for any help.
# 2  
Old 09-10-2012
What have you tried with sed?
# 3  
Old 09-10-2012
Read in two lines at once with the "N" subcommand, then insert after the "\n", which is the newline separating the lines:

Code:
sed 'N;s/\n/&=changes here=/p'

In case of files with uneven numbers of lines you will have to introduce a special rule for the last line ("$"), otherwise the last line will not be printed.

I hope this helps.

bakunin
# 4  
Old 09-10-2012
Something simpler and what you require:
Code:
cat testfile
ABCD
EFGH
IJKL
MNOP
PQRS

sed 's/.*/NEW TEXT &/;n' testfile
NEW TEXT ABCD
EFGH
NEW TEXT IJKL
MNOP
NEW TEXT PQRS

This User Gave Thanks to elixir_sinari For This Post:
drbiloukos
# 5  
Old 09-10-2012
with awk..Smilie

Code:
awk 'NR%2{$0="some text "$0}1' file

This User Gave Thanks to pamu For This Post:
drbiloukos
# 6  
Old 09-10-2012
Another sed variation - if you have GNU sed you could use an address with a step, e.g.
Code:
carlo@host:/tmp -> sed '1~2s/.*/NEW TEXT &/' testfile
NEW TEXT ABCD
EFGH
NEW TEXT IJKL
MNOP
NEW TEXT PQRS

# 7  
Old 09-11-2012
Thank you all for your help.
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