Replace config file variables using bash script

Question

I tried to append a value to the ssh config file but it seems that it doesn't work if specify two different values, it reads the first not the second.

It seems sensible, instead of trying to re-write the entire file, to just modify the value.

Currently the value is:

Port 22

I want to go in and change the value to:

Port 222

The best I can come up with is this:

sed -c -i "s/\(Port *= *\).*/\1$REPLACEMENT_VALUE/" /etc/ssh/sshd_config

However I know this isn't right because it's working in a way where it is expecting to have an equals sign between the value and the variable.

I need the script to do something like this:

Look for the variable (i.e Port)
Switch this line with my own line

Avinash Raj · Accepted Answer · 2015-03-15 10:45:33Z

3

I think you mean this,

sed 's/.*\bPort\b.*/REPLACEMENT_VALUE/' file

Example:

$ REPLACEMENT_VALUE="Port 222"
$ echo -e "foo\nPort 22" | sed "s/.*\bPort\b.*/$REPLACEMENT_VALUE/"
foo
Port 222

edited Mar 15, 2015 at 10:45

answered Mar 15, 2015 at 10:40

Avinash Raj

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3 Comments

Jimmy Over a year ago

Thank you. Do I need the i flag to change in place? Also the replacement value would read "Port 222" not "222", right?

Avinash Raj Over a year ago

add -i parameter to do an in-place edit. sed -i 's/.*\bPort\b.*/REPLACEMENT_VALUE/' file

Avinash Raj Over a year ago

if the replacement value is present inside a variable then you need to enclose the sed code within double quotes.

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