`logname': Print current login name
===================================
`logname' prints the calling user's name, as found in the file
`/var/run/utmp', and exits with a status of 0. If there is no
`/var/run/utmp' entry for the calling process, `logname' prints an
error message and exits with a status of 1.
The only options are `--help' and `--version'. Note:Common
options.