The clockdiff command in Linux is used to measure the time difference between two Linux hosts. This command is useful for network administrators who need to ensure that all the hosts on their network are synchronized and running on the same time.
Overview
The syntax of the clockdiff command is as follows:
clockdiff [options] host1 host2
where host1 and host2 are the two hosts between which the time difference needs to be measured.
Here are some examples of how to use the clockdiff command:
- To check the time difference between two hosts
192.168.1.100and192.168.1.200:
clockdiff 192.168.1.100 192.168.1.200
- To check the time difference between the local host and a remote host
example.com:
clockdiff localhost example.com
The output of the clockdiff command will display the time difference between the two hosts in seconds.
Options
The following table lists the available options for the clockdiff command:
| Option | Description |
|---|---|
| -a | Display the average time difference between the hosts. |
| -c N | Send N packets to each host (default is 3). |
| -w N | Wait for N seconds for a response (default is 5). |
| -n | Do not attempt to resolve hostnames. |
| -v | Verbose output. |
Troubleshooting tips
Here are some common issues that may be encountered while using the clockdiff command:
- If the
clockdiffcommand is not found, make sure that it is installed on the system. On Debian-based systems, it can be installed using the following command:
sudo apt-get install iputils-clockdiff
- If the command returns an error stating that the host cannot be resolved, ensure that the hostname or IP address of the host is correct and that the DNS resolution is working correctly.
Notes
- The
clockdiffcommand uses the ICMP protocol to send packets between the hosts and measure the time difference. - The time difference measured by the
clockdiffcommand may not be accurate if the network latency is high or if the hosts are located in different time zones.