To set the maximum lifetime for ssh-agent in seconds, you can use the -t option followed by the number of seconds.
For example, to set the maximum lifetime to 3600 seconds (one hour), you can use the following command:
ssh-agent -t 3600
This will start an ssh-agent with a maximum lifetime of 3600 seconds.
You can also set the maximum lifetime for ssh-agent by setting the SSH_AUTH_SOCK_LIFETIME environment variable. For example:
export SSH_AUTH_SOCK_LIFETIME=3600 ssh-agent
This will start an ssh-agent with a maximum lifetime of 3600 seconds.
Note that the maximum lifetime for ssh-agent only affects the lifetime of the ssh-agent process itself, and not the lifetime of the keys that are added to it. To set the lifetime of added keys, you can use the ssh-add -t option followed by the number of seconds.
For example, to set the lifetime of added keys to 3600 seconds (one hour), you can use the following command:
ssh-add -t 3600
Overall, the -t option and the SSH_AUTH_SOCK_LIFETIME environment variable are useful tools for setting the maximum lifetime for ssh-agent in seconds. They allow you to customize the lifetime of the ssh-agent process and ensure that it does not remain active for longer than necessary.