The syntax for ssh-agent is:
ssh-agent [-c] [-d debug_level] [-h] [-k] [-s] [-t timeout] [-V] [command]
Options are available in both a single-character form (such as -o) and a descriptive equivalent (--option). Single characters are shown here. To view the descriptive equivalents, use the -h command line option.
Forces the shell to be csh. By default ssh-agent uses the SHELL environment variable to determine which shell to invoke. This option overrides the default behavior.
Sets the debug level. Increasing the value increases the amount of information displayed. Use 1, 2, 3, or 99. (Values 4-98 are accepted, but are equivalent to 3.)
Displays a brief summary of command options.
Kills the current agent (given by the SSH_AGENT_PID environment variable).
Forces the shell to be sh. By default ssh-agent uses the SHELL environment variable to determine which shell to invoke. This option overrides the default behavior.
Sets a default timeout for any key added to the agent. Keys are deleted after the specified timeout. By default keys have no timeout limit, which is equivalent to setting a timeout value of zero(0). (You can also specify timeouts when you add keys by using the ssh-add -t option, which overrides this setting.)
By default, the timeout value is set in minutes. You can specify other units using this syntax:
n<unit>[n<unit>…]
Where unit can be: s (seconds), m (minutes), h (hours), d (days), or w (weeks). (Upper or lower case units are both accepted with the same meaning.) For example:
3600s = 3600 seconds (1 hour)
2w = 2 weeks
2d4h = 2 days and 4 hours
Displays product name and version information and exits. If other options are specified on the command line, they are ignored.