Keep existing DNS servers in office and append 192.0.2.53.
Which command is appropriate?
Prefixing a list property with + appends a value; - removes it and an unprefixed assignment can replace the list.
Detailed explanation
nmcli con mod office ipv4.dns 192.0.2.53Incorrect. An unprefixed assignment can replace existing DNS values.
Incorrect. An unprefixed assignment can replace existing DNS values.
nmcli con mod office -ipv4.dns 192.0.2.53Incorrect. A leading minus removes a value.
Incorrect. A leading minus removes a value.
nmcli con mod office +ipv4.dns 192.0.2.53Correct. +ipv4.dns appends the server to the existing list.
Correct. +ipv4.dns appends the server to the existing list.
nmcli con show office +ipv4.dns 192.0.2.53Incorrect. connection show is read-only.
Incorrect. connection show is read-only.
Try it yourself
An example you can run in a temporary verification environment.
printf '%s
' '+ipv4.dns -> append' '-ipv4.dns -> remove'Expected result
+ipv4.dns -> append
-ipv4.dns -> removeKey points
- + appends
- - removes
- Unprefixed may replace
Notes
- Environment: property操作の表示のみ
- Command output formatting can vary slightly by distribution or tool version.
- Run the example in a temporary directory or process when possible.
Foundation review
Read the scope first
Check whether the command acts on the current shell, a new process, an existing process, or a file.
Verify the observable result
Use the supplied command and compare the output with the expected result.