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Remove a line from a file using sed (useful for updating known SSH server keys when they change)

Terminal - Remove a line from a file using sed (useful for updating known SSH server keys when they change)
perl -p -i -e 's/.*\n//g if $.==2' ~/.ssh/known_hosts
2012-01-17 14:11:03
User: meappy
Functions: perl
-1
Remove a line from a file using sed (useful for updating known SSH server keys when they change)

Easily removes line #2 in ~/.ssh/known_hosts.

Alternatives

There are 6 alternatives - vote for the best!

Terminal - Alternatives
ssh-keygen -R <thehost>
sed -i '${LINE}d' ~/.ssh/known_host
vi +<lineNumber>d +wq <filename>
2012-01-25 18:28:03
User: detert
Functions: vi
1

For example, to remove line 5 from foo, type: vi +5d +wq foo

sed '${LINE}d' ~/.ssh/known_host
2012-01-16 18:00:12
User: lucasrangit
Functions: sed
-5

When you SSH to a server who's hostname or IP has changed since the last time a connection was recorded in the known_hosts file a warning will be displayed since this indicated a possible DNS spoofing attack. If this is a known change then this command will remove the previous entry and allow the SSH connection. The SSH client will prompt you as if it was the first time connected to the server.

Replace ${LINE} with the line of the offending key in ~known_hosts. 49 in the sample output.

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