LinuxQuestions.org - [SOLVED] Add symbol to the end of every other line

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Add symbol to the end of every other line

Hello everyone,

I'm sure that this is extremely simple, but don't understand the sed command enough to do it myself.

Basically, if I have a list such as that below, I want to add a ; symbol to the end of every other line:

NOOB_1
abcdefghijklmn
NOOB_2
abcdefggggghigglfkj
NOOB_1245
abcddefiigohgggg

So I want to alter the above to give the following:

NOOB_1
abcdefghijklmn;
NOOB_2
abcdefggggghigglfkj;
NOOB_1245
abcddefiigohgggg;

Thanks to anyone that can help. I have managed to add a symbol to the end of EVERY line, but not every OTHER line.

Have a look at this:

Code:

gawk '{ if ( NR%2 != 1 ) { print $0";" } else { print } }' infile

Code:

sed -i '0~2s/$/;/' file

From the sed manual page:

Code:

The following address types are supported:



first~step

      Match every step'th line starting with line first.  For example,

      ``sed -n 1~2p'' will print all the odd-numbered lines in the input

      stream, and the address 2~5 will match every fifth line, starting

      with the second.

That's perfect. Thank you both. I'm getting the hang of sed now :)