Only the superuser can write on the terminals of users who have chosen to deny messages or are using a program which automatically denies messages.
Reading from a file is refused when the invoker is not superuser and the program is set-user-ID or set-group-ID.
- -n, --nobanner
- Suppress the banner.
- -t, --timeout timeout
- Abandon the write attempt to the terminals after timeout seconds. This timeout must be a positive integer. The default value is 300 seconds, which is a legacy from the time when people ran terminals over modem lines.
- -g, --group group
- Limit printing message to members of group defined as a group argument. The argument can be group name or GID.
- -V, --version
- Display version information and exit.
- -h, --help
- Display help text and exit.