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What is the best method for editing the /root/.ssh/authorized_keys file?

I mean if I need to append a new key to my authorized_keys file, than what are the best methods to do that?

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Try just to edit the file and paste key on the end.
You want automated? Try from server where you want to add key to do:

ssh-copy-id -i id_rsa.pub login@hostname

You can always try ssh-add on the server where you have an authorized_keys file stored.

Plenty of opportunities :D

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Also cat keyfile >>authorized_keys – enzotib Dec 17 '11 at 15:12
What should go as hostname ? – User Nov 3 '15 at 0:19

Each line is an independent entry. You can grep them to filter, sed -i~ /pattern/d authorized_keys to delete lines, say all those from some server, or cat new-entries >> authorized_keys to add lines to the end.

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there is two problem with "cat new-entries >> authk. – LanceBaynes Dec 18 '11 at 15:34
1) people could mistype ">>" to ">" so the file is gone.. – LanceBaynes Dec 18 '11 at 15:35
2) if there isn't any newline char in the authorized_keys file, then cat/echo will append the new public key to the end of the last line... :\ – LanceBaynes Dec 18 '11 at 15:35
The cat method is the one most frequently used and suggested. If it doesn't end in a newline, it's not a well-formed text file. – Kevin Dec 18 '11 at 17:53
@Lance: Wrt. 1, I can't say I've ever done that, but if you are prone to this kind of thing, try using sed -i~ 'r$ new-entries', since that creates a backup file. Wrt. 2., this is easily enough fixed with a text editor, and as Kevin says, you should pay a bit of attention to the semantics of what you are doing. – Charles Stewart Dec 18 '11 at 18:55

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